Sonoma County Water Agency (PDF) - State of California

TABLE OF CONTENTSiiPage1.0 INTRODUCTION ...............................................................................................................11.1 AGENCY PROFILE................................................................................................11.2 PURPOSE OF THE PLAN......................................................................................21.3 PLAN DEVELOPMENT PROCESS ......................................................................31.3.1 Water System Reliability Study...................................................................41.3.2 Document Review........................................................................................41.3.3 Public Involvement ......................................................................................51.4 PLAN ADOPTION..................................................................................................62.0 SONOMA COUNTY WATER AGENCY FACILITIES ...................................................72.1 WATER SUPPLY SYSTEM...................................................................................72.2 SANITATION SYSTEM.........................................................................................82.3 FLOOD CONTROL SYSTEM................................................................................92.4 EMERGENCY POWER........................................................................................102.5 ADMINISTRATIVE INFRASTRUCTURE.........................................................103.0 HAZARD ASSESSMENT ................................................................................................123.1 EARTHQUAKE HAZARD...................................................................................123.1.1 Historic Seismicity.....................................................................................123.1.2 Surface Fault Rupture Hazard....................................................................133.1.3 Strong Ground Shaking..............................................................................143.1.4 Liquefaction and Lateral Spread................................................................153.1.5 Earthquake Induced Landslides .................................................................163.2 FLOOD HAZARD.................................................................................................173.3 GEO-HAZARDS ...................................................................................................193.3.1 Landslides ..................................................................................................193.3.2 Corrosive Soils...........................................................................................193.4 FIRE HAZARD .....................................................................................................213.5 DROUGHT............................................................................................................233.6 OTHER HAZARDS ..............................................................................................253.6.1 Tornadoes...................................................................................................273.6.2 Hurricanes and Other Weather Related Hazards .......................................273.7 HAZARDS SUMMARY.......................................................................................284.0 VULNERABILITY ASSESSMENT.................................................................................294.1 WATER SUPPLY .................................................................................................294.1.1 Russian River System ................................................................................304.1.2 Diversion Facilities ....................................................................................304.1.3 Aqueducts ..................................................................................................314.1.4 Storage Facilities........................................................................................324.1.5 Booster Pump Facilities .............................................................................334.1.6 Treatment Facilities ...................................................................................334.1.7 Supplementary Water Sources...................................................................344.1.8 Emergency Power ......................................................................................34

4.2 SANITATION .......................................................................................................344.3 FLOOD PROTECTION ........................................................................................364.4 ADMINISTRATIVE INFRASTRUCTURE.........................................................365.0 MITIGATION GOALS, OBJECTIVES AND ACTIONS................................................376.0 IMPLEMENTATION STRATEGY..................................................................................427.0 PLAN MAINTENANCE...................................................................................................457.1 MONITORING EVALUATING AND UPDATING THE PLAN .......................457.2 CONTINUED PUBLIC INVOLVEMENT...........................................................458.0 REFERENCES ..................................................................................................................47iii

TABLESTable 1Table 2Table 3Table 4Table 5Table 6Peak Ground Acceleration (g) at the Agency’s FacilitiesHistoric Floods in Sonoma CountyMajor Historic Fires in Sonoma CountyHistoric Weather Related Hazards in Sonoma CountyFujita Scale for Tornado IntensityHazard SummaryFIGURESFigure 1 Water System MapFigure 1a Water System Map (Wohler-Mirabel Area)Figure 2 Sanitation District and ZonesFigure 3 Power SystemFigure 4 Fault MapFigure 5 Historic Earthquakes in the Bay AreaFigure 6 Earthquake Probabilities in the Bay AreaFigure 7 Fault Map for the Agency’s Water Transmission System Service AreaFigure 8 Ground Shaking Hazard Map (Water Transmission System)Figure 9 Liquefaction and Lateral Spread Hazard (Water Transmission System)Figure 10 Landslide Hazard (Water Transmission System)Figure 11 Flood Hazard (Water Transmission System)Figure 12 Historic Landslides in Sonoma County during El Nino Storms of 1997-1998Figure 13 Debris Flow Hazard (Water Transmission System)Figure 14 Concrete Corrosion Potential (Water Transmission System)Figure 15 Steel Corrosion Potential (Water Transmission System)Figure 16 Fire Threat (Water Transmission System)Figure 17 Historic Fires in Sonoma County (Water Transmission System)Figure 18 Tornado Hazard in CaliforniaFigure 19 Fault Map for the Agency’s Sanitation System Service AreaFigure 20 Ground Shaking Hazard Map (Sanitation System)Figure 21 Liquefaction and Lateral Spread Hazard (Sanitation System)Figure 22 Landslide Hazard (Sanitation System)Figure 23 Flood Hazard (Sanitation System)Figure 24 Debris Flow Hazard (Sanitation System)Figure 25 Concrete Corrosion Potential (Sanitation System)Figure 26 Steel Corrosion Potential (Sanitation System)Figure 27 Fire Threat (Sanitation System)Figure 28 Historic Fires in Sonoma County (Sanitation System)iv

1.0 INTRODUCTION1.1 AGENCY PROFILEThe Sonoma County Water Agency (Agency) was created as a special district in 1949 by theCalifornia Legislature to provide flood protection and water supply services to portions ofSonoma and Marin counties. Legislation enacted in 1995 added the treatment and disposal ofwastewater to the Agency's responsibilities. Although the Sonoma County Board of Supervisorsacts as the Agency's Board of Directors, the Agency is a separate legal entity created by Statelaw, having specific limited purposes and powers, and separate sources of funding. The Agencyis thus different from County departments, which are created by the Board of Supervisors foradministrative purposes, but are not separate legal entities.The Agency is a wholesale water supplier to eight primary water contractors, several smallercommunities and water companies, a range of surplus (curtailable) customers and off-peakcustomers. The total population served by the Agency is approximately 600,000 people insouthern Sonoma County and Marin County. The projected total annual water demand from theAgency’s customers is approximately 74 mgd for 2010 to 96 mgd for 2030.The Agency also provides wastewater collection and treatment, and recycled water distributionand disposal services to approximately 22,000 residences and businesses and maintains morethan 70 miles of engineered flood control channels and over 80 miles of natural channels(creeks). As part of flood control works, the Agency also maintains levees, and fish ladders, andembankment protection on the Russian River.The Agency’s eight prime water supply customers include the City of Santa Rosa, North MarinWater District, City of Petaluma, City of Rohnert Park, Valley of the Moon Water District, Cityof Sonoma, City of Cotati and Town of Windsor. Approximately 2% of the Agency’s water issupplied to customers such as California-American Water Company (Larkfield District),Penngrove Water Company, Lawndale Mutual, Kenwood Village Water Company, ForestvilleWater District, and various government entities. Depending upon the Agency’s transmissionsystem capacity and the availability of excess water in the Russian River, the Agency sells asmuch as 12% of its water to the Marin Municipal Water District (MMWD). However,MMWD’s rights to Agency’s transmission system capacity are subordinate to the rights of theAgency’s eight prime contractors. Less than 1% of Agency’s total water deliveries are providedto several curtailable (surplus customers) such as local wineries.Each of the Agency’s water contractors is responsible for maintaining their own retaildistribution system, including storage tanks and pumping stations. Most of the Agency’s water1 Sonoma County Water Agnecy.doc

contractors maintain some local source of supply in addition to water purchased from theAgency, but that constitutes a very small percentage of their total water requirements. Water toits various contractors is provided through tie-ins into the Agency’s aqueducts. In addition to thecontractor tie-ins into the aqueducts, the transmission system is also tied to about thirty firehydrants. However, the primary fire-fighting capability within the Agency’s service area isthrough fire hydrants within the local distribution systems.The Agency is also responsible for wastewater collection, treatment and disposal services for theAirport/Larkfield/Wikiup, Geyserville, Penngrove and Sea Ranch County Sanitation Zones andthe Occidental, Russian River, Sonoma Valley, and South Park County Sanitation Districts. Forflood control purposes, the Agency has helped build and manage the Warm Springs Dam, SpringLake, Coyote Valley Dam, Matanzas Creek Reservoir, Piner Creek Reservoir, Brush CreekReservoir.1.2 PURPOSE OF THE PLANSonoma County is located in an area impacted by multiple natural hazards. Historically it hasbeen subjected to many floods, wildfires, landslides and mudflows. Due to its proximity to theSan Andreas Fault System, one of the major active fault systems in the world, Sonoma Countyalso has a very high earthquake hazard.The Agency’s water, wastewater and flood control systems are distributed over a largegeographical area and traverse zones of varying geology and potential hazards. Acomprehensive Hazard Mitigation Plan (Plan) was prepared in recognition of the Agency’sresponsibility to the community and its role in preserving the economic vitality of the region. Asstated in the Sonoma County Emergency Operations Plan, the public places trust in the operatorsof water systems to provide high quality drinking water, even after a disaster. An uninterruptedsupply of clean drinking water and water for fire fighting is essential for the health and safety ofthe community and to minimize the potential for loss of life and property damage following amajor natural disaster.As has been shown numerous times in the past, natural disasters can result in enormous cost tothe public through loss of life, human suffering, property damage and economic loss. Lack ofpreparedness can make recovery a very long and arduous process, which can last for manymonths or years and can depress a region for a time long after the physical signs of the disasterhave disappeared. Recognizing this, the Federal Government passed the Disaster Mitigation Actof 2000 (DMA 2000), which encourages and rewards pre-disaster planning at all levels of local,tribal and State government.2 Sonoma County Water Agnecy.doc

As an incentive for pre-disaster mitigation planning, the DMA 2000 has established a predisasterhazard mitigation program and new requirements for the national post-disaster HazardMitigation Grant Program (HMGP). Accordingly, a larger amount of HMGP funds are availablefor communities that have developed a comprehensive mitigation plan prior to a disaster. Inaddition States, tribes and communities must have an approved mitigation plan in place beforereceiving HMGP funds. In addition, the Federal Emergency Management Agency (FEMA) hasa Pre-Disaster Mitigation (PDM) program that provides funds to states, territories, Indian tribalgovernments, communities, and universities for hazard mitigation planning and theimplementation of mitigation projects prior to a disaster event. Funding these plans and projectsreduces overall risks to the population and structures, while also reducing reliance on fundingfrom actual disaster declarations. PDM grants are awarded on a competitive basis and withoutreference to state allocations, quotas, or other formula-based allocation of funds. An approvedHazard Mitigation Plan is a pre-requisite for applying for a PDM grant.1.3 PLAN DEVELOPMENT PROCESSRecognizing its obligation to provide high quality water to the public, the Agency on its owninitiative in 2004 embarked on a natural hazard reliability improvement program for its watersupply system. This multi-phase project was initiated by the Department of Engineering andResource Planning, with the Agency’s Capital Projects Manager, Mr. Cordel Stillman, as theProject Manager for the project. Throughout the course of the project Deputy Chief Engineersfrom the Agency’s Engineering and Resource Planning Division (Mr. James Jasperse),Maintenance Division (Mr. Michael Thompson) and Operations Division (Ms. Pamela Jean)were involved in setting the course of the project, attended meetings and reviewed drafts of theplan.The Agency contracted the services of MMI Engineering (MMI), a specialty engineering firmwith expertise in the assessment of natural and man-made hazards and their impact on watersystem reliability. The MMI team included specialists in structural/earthquake engineering,geotechnical/foundation engineering, geology and tectonics, engineering seismology, pipelineperformance, hydrology, risk analysis, water resources and economic analysis. To involve theAgency’s staff at all levels and not just management and to obtain their buy-in, a one dayworkshop was conducted to discuss the philosophy of the program and its approach and to obtainfeedback. During the course of the work MMI’s engineers interacted with Agency’smaintenance, operations and engineering staff at many levels to obtain intelligence andoperational knowledge of the Agency’s system. MMI and Agency management staff met withthe Agency’s contractors at all significant decision points to receive input.3 Sonoma County Water Agnecy.doc

1.3.1 Water System Reliability StudyThe initial phase of the project included identification of all credible natural hazards that couldimpact the system. The effects of each hazard (for example, expected ground accelerations in anearthquake, available fuel for wild fires, flood maps and zones of liquefaction and landslide)were plotted on a detailed Geographical Information System (GIS) map of the Agency’s watersystem. This information was used to perform a preliminary assessment of the water systemvulnerabilities to these hazards.In the preliminary assessment, threats to the system that resulted in the greatest impact in theAgency’s ability to reliably meet its mandate were identified. Since the benefits of hazardmitigation are a reduction in potential losses, vulnerabilities that could result in greatest losseswere identified with the belief that, if mitigated, they would likely produce the greatest benefits.The preliminary assessment identified earthquakes and earthquake related hazard as the mostsignificant hazards to the Agency’s infrastructure followed by flood and fire. However, thevulnerability of Agency’s facilities to flood and fire were significantly below the seismicvulnerability.Following this preliminary assessment a more comprehensive assessment of Agency’s facilitiesidentified as potentially vulnerable was conducted through detailed structural, geotechnical andgeological analysis including, as needed, subsurface investigations. In this study, which isnearing completion, the impact of these hazards and system vulnerabilities in terms of watersupply to the Agency’s contractors was studied through a detailed hydraulic model of the system.Based on these assessments a Capital Improvement Program (CIP) has been prepared thatidentifies mitigation actions through a combination of pre-hazard planning, system upgrades,component retrofits and plans for post-hazard repair.The results of the preliminary and comprehensive assessments were presented to the Agency in aseries of reports and technical memoranda. Prior to finalizing, the reports and memoranda werefirst submitted to the Agency in draft form. [1-7] The draft reports were circulated within theAgency to the Deputy Chief Engineers of the Engineering and Resource Planning, Maintenanceand Operations Divisions for their comments.1.3.2 Document ReviewThis plan has been developed through an extensive review of available information on hazards,Agency’s emergency response plans, [8,9] Agency’s urban water management plans, [10]4 Sonoma County Water Agnecy.doc

engineering drawings and reports for Agency’s facilities (Appendix A), historic aerialphotographs and available geotechnical and geologic data both from the Agency and outsidesources (for example, California Geological Survey for detailed fault investigation reports,California Department of Transportation for geotechnical reports).In addition to the risk assessment of Agency’s water supply facilities conducted as part of watersupply reliability improvement program, an overview of the general vulnerabilities of theAgency’s wastewater and flood control facilities is included in the development of this plan.Other documents such as the FEMA 386 [11-16] series of documents the Sonoma County’s CountyHazard Mitigation Plan, [17] and FEMA approved plans for other entities. [18,19]1.3.3 Public InvolvementStakeholder involvement during this process included meetings with the Agency’s eight primarywater supply contractors to describe the Agency’s objectives, solicit input and apprise them ofthe findings of the hazard assessments. The Agency’s General Manager and Board of Directors(who are also the County’s Board of Supervisors) have also been kept informed of the ongoingwork. To involve the Agency’s staff at all levels and not just management and to obtain theirbuy-in, a one day workshop was conducted to discuss the philosophy of the program and itsapproach and to obtain feedback. During the course of the work MMI’s engineers interactedwith Agency’s maintenance, operations and engineering staff at many levels to obtainintelligence and operational knowledge of the Agency’s system.After completing the preliminary water system reliability study, the Agency’s contractors werebriefed in a series of two hour meetings attended by the contractor representatives, MMI ProjectManager and the Agency’s Capital Projects Manager and the Deputy Director Engineering andResource Planning. [20-24]The following additional activities are planned as part of public involvement process:• The draft hazard mitigation plan posted on the Agency’s website on November 6, 2007 forpublic review and comment.• The draft hazard mitigation plan presented to the Agency’s Water Advisory Committee(WAC) on November 5, 2007 for review and comment.• The draft hazard mitigation plan presented to the Agency’s Technical Advisory Committee(TAC) on November 5, 2007 for review and comment.5 Sonoma County Water Agnecy.doc

• The draft hazard mitigation plan presented to the Agency’s contractors for review andcomment as follows:o City of Santa Rosa, October, 2007o City of Sonoma, October, 2007o City of Petaluma, October, 2007o Town of Windsor, October, 2007o City of Rohnert Park, October, 2007o City of Cotati, October, 2007o North Marin Water District, October, 2007o Valley of the Moon Water District, October, 2007• The draft hazard mitigation plan presented to the Agency’s Board of Supervisors on January8, 2008 for review, comment and formal adoption.No comments on the Plan were received from the public. Several minor comments werereceived from the Agency’s contractors which were incorporated into the Plan.1.4 PLAN ADOPTIONThis plan was formally adopted by the Sonoma County Water Agency Board of Supervisors onJanuary 8, 2008. The formal resolution of adoption is included in Appendix B.6 Sonoma County Water Agnecy.doc

2.0 SONOMA COUNTY WATER AGENCY FACILITIES2.1 WATER SUPPLY SYSTEMThe Agency’s water system is shown in Figure 1 and Figure 1a. The primary source of water forthe Agency’s water supply system is a ground water aquifer located in the Mirabel Park area justnorth of the town of Forestville. The aquifer is located adjacent to the Russian River andreceives water from the river by natural filtration through an approximately 60 feet thick sandand gravel riverbed. Water from the aquifer is pumped by six Ranney type collector wells andreleased into 83 miles of large diameter pipelines (aqueducts) that transmit water throughout theAgency’s service area. Three out of the six collectors are located along the eastern bank of theriver in the Wohler area and are referred to the Wohler collectors, while the remaining three arelocated along the western bank of the river in the Mirabel area and are known as the Mirabelcollectors. On the average, the Mirabel and Wohler collectors can provide a sustained flow ofapproximately 15 mgd each. In addition to the collector wells, the water supply system has tenconventional wells (with an average sustained flow of 7 mgd) that supplement the water supplyfrom the collectors. Seven of these wells are located along the Russian River in the generalvicinity of the collectors, while the remaining three are located in the Laguna De Santa Rosa areanear Sebastopol.The transmission system has eight booster pump stations that provide the necessary head tomove the water through the system. Water storage is provided by 18 steel storage tanks with acollective storage capacity of 128.8 million gallons. The Agency also maintains two majorreservoirs impounded by two large dams (heights of 319 feet and 160 feet), an inflatable rubberdam, a system of ditches, infiltration ponds and a dike, three water treatment facilities, an electricpower substation, a hydroelectric plant, and several emergency power generators.The key facilities that constitute Agency’s water supply system are summarized below:• Russian River system – includes the Russian River, the Russian River aquifer and the WarmSprings and Coyote Valley dams (319 feet high and a 164 feet high earth-fill embankmentdams).• Diversion system – includes collector wells, inflatable dam, River Diversion Structure(RDS), Mirabel well field, dikes and diversion channels in the Wohler-Mirabel area andinfiltration ponds.• Transmission system – includes all of the Agency’s aqueducts that transport water from theAgency’s diversion system facilities to storage and to its contractors.• Storage system – includes 18 storage tanks that provide 128.8 million gallons of storage.7 Sonoma County Water Agnecy.doc

• Pumping facilities – includes 8 booster stations.• Treatment facilities – includes three chlorination and corrosion control facilities.• Power system – includes the electric substation, fixed and portable emergency generators andthe 12kv power line.• Supplementary facilities – includes Laguna de Santa Rosa wells and the Agency’s office andoperations buildings.• Equipment and non-structural components – Most of the Agency’s facilities that includeboosters stations, pump houses at the collectors, chlorination and corrosion control facilities,wells and office buildings house a range of equipment and non-structural components, whichif unanchored are vulnerable to damage or can either cause injury or damage to an adjacentcritical piece of equipment.2.2 SANITATION SYSTEMThe Agency’s sanitation system includes eight Sanitation Districts and Zones. The service areafor the zones (systems owned by the Agency) and districts (independent special districts operatedby the Agency) varies from 70 to 4600 acres. Figure 2 shows the location of the 8 sanitationdistricts/zones. Each district/zone has its own wastewater collection system that typicallyincludes gravity flow in pipelines. Out of the eight districts/zones, six have wastewater treatmentplants. The remaining two, the Penngrove Sanitation Zone and the South Park County SanitationDistrict, collect wastewater and transport it to the City of Petaluma and the City of Santa Rosatreatment facilities, respectively. The total pipeline length for each district/zone ranges from aslittle as one mile for the Occidental County Sanitation District to over 100 miles for the SonomaValley Sanitation District. The Agency has 29 lift stations located across these systems. Thewastewater treatment plants treat wastewater to either secondary or tertiary standards and includea series of aeration basins, settling ponds, clarifiers, holding ponds, chlorination chambers anddechlorination facilities.The average dry weather flow for the treatments plants vary from 2000 gallons per day (SeaCentral Sanitation Zone) to 2.8 mgd (Sonoma Valley County Sanitation District). Aftertreatment, the wastewater is either used for irrigation or discharged to percolation ponds orwaterways. The Geyserville and Sea Ranch North Sanitation Zone use percolation ponds todischarge the treated wastewater. Some recycled water from the Sonoma Valley CountySanitation District is discharged through Shell Slough which ultimately flows into the San Pablo8 Sonoma County Water Agnecy.doc

Bay. Recycled water from the Russian River County Sanitation District and Occidental CountySanitation District ultimately flows into the Russian River.2.3 FLOOD CONTROL SYSTEMThe Agency, in cooperation with the United States Army Corps of Engineers (USACE), isresponsible for maintaining specific federal and non-federal flood control improvement projectson the Russian River. The Agency’s flood control works include Lake Mendocino, LakeSonoma, the Central Sonoma Watershed Project and the Laguna De Santa Rosa.Lake Mendocino is located on the East Fork Russian River three miles northeast of Ukiah. Itwas formed by the construction of the Coyote Valley Dam by the United States Army Corps ofEngineers (USACE) in 1959. The dam is a 160-foot high rolled earth embankment used forwater storage and flood control purposes. The Agency and the Mendocino County RussianRiver Flood Control and Water Conservation Improvement District share permits by the State forrights to store up to 122,500 acre-feet of water per year in the reservoir. However, the Agencyhas the exclusive right to control the releases of water from the water supply pool in LakeMendocino because it was the local sponsor for the dam project. When the water level risesabove the top of the water supply pool and into the flood control pool the USACE assumescontrol of releases.Lake Sonoma is located approximately 14 miles northwest of Healdsburg at the confluence ofWarm Springs Creek and Dry Creek. The reservoir was formed by the construction of WarmSprings Dam, a 319-foot high rolled earth dam, in 1982 by the USACE. Similar to LakeMendocino, the Agency has exclusive rights to control the rate of release of water from the watersupply pool in Lake Sonoma. When the water level in the Lake rises above elevation 451 feetand goes into the flood control pool, the USACE assumes control of the water release. TheAgency has constructed and operates a 2.6 mega watt hydropower plant at the dam.The Central Sonoma Watershed Project includes four flood control reservoirs that include theSanta Rosa Creek Reservoir (Spring Lake), Matanzas Creek Reservoir, Piner Creek Reservoir,and the Brush Creek Middle Fork Reservoir. Each of these reservoirs are equipped withappurtenant structures but unlike the Warm Springs and Coyote Valley dams they are notequipped with flood gates and instead operate passively either as detention basins or bypasssystems. Several waterways have also been shaped and stabilized as part of the Central SonomaWatershed Project.The Laguna de Santa Rosa is a natural overflow basin covering 254 square miles and connectsthe Mark West creek and other smaller creeks with the Russian River.9 Sonoma County Water Agnecy.doc

The Agency provides maintenance services for over 150 miles of engineered and naturalchannels (creeks) in addition to the maintenance of the Central Sonoma Watershed reservoirsand upper Russian River channel and levee maintenance. The Agency’s maintenance activitiesinclude debris removal, bank stabilization and protection, maintenance of inlet/outlet structures,silt removal, vegetation management, levee repair, service road maintenance and dam andreservoir structure maintenance. The Agency also maintains several gauging stations along theRussian River that provide information on rainfall intensity, river height and discharge that isessential to flood forecasting.2.4 EMERGENCY POWERElectrical power to operate the Agency’s booster pumps and equipment is provided by the Powerand Water Resources Pooling Authority (PWRPA) and Pacific Gas and Electric Company(PG&E). Power to the collector wells is provided by an Agency owned and operated substationlocated at the Wohler Corporation Yard. Power from the substation is supplied to the collectorsat Wohler and Mirabel through a 12-kV power-line that runs along the river and infiltrationponds as shown in Figure 3.The Agency has provisions to provide emergency electrical power for its main pumps at thecollector wells. Three fixed place emergency generators are located at the Wohler CorporationYard. These generators can run any combination of pumps, up to a maximum of six, at both theWohler and Mirabel collectors. The Mirabel facility has two fixed place 480 volt, 1100 kWdiesel generators that can operate two of the main pumps at Mirabel. The diesel generators arefueled by two diesel fuel tanks, a 10,000 and a 25,000 gallon, located at each generator site.Emergency power to the booster pumping stations and emergency wells can be provided byportable trailer mounted 480 volt generators. In addition, fixed place diesel generators are alsolocated at the Sonoma No. 2 booster station and the Ely Road booster station.The Operations and Maintenance Center, Service Center and Administration Buildings atCollege Avenue have standby generators that operate automatically when power is lost.2.5 ADMINISTRATIVE INFRASTRUCTUREThe Agency owns two office facilities located on 404 Aviation Boulevard and 2150 WestCollege Avenue in Santa Rosa. The Aviation Boulevard facility is the Administration Buildingand houses a majority of the Agency’s engineering, administration, accounting, environmental,public affairs and executive management staff. The College Avenue facility is occupied by theoperations and maintenance staff, equipment and the supervisory control and data acquisition10 Sonoma County Water Agnecy.doc

(SCADA) system. The College Avenue facility also has a Service Center where maintenanceand management of Agency fleet vehicles and gas-powered equipment is also performed. TheAdministration Building is powered by solar photovoltaic panels that have been installed on thebuilding roof and on ground-mounted power canopy.11 Sonoma County Water Agnecy.doc

3.1 EARTHQUAKE HAZARD3.0 HAZARD ASSESSMENTSonoma County is the northernmost of the nine counties that constitute the seismically veryactive San Francisco Bay Area. Earthquakes in the Bay Area occur due to a sudden slip on oneof the several major faults of the San Andreas Fault system. The slip releases tremendousamount of strain energy stored along these faults from the relative movement (approximately 2inches per year) between the Pacific oceanic plate and the North American continental plate.When the accumulated strain on the fault reaches the threshold strength of rock in the earth’scrust, it is released in an earthquake by a sudden rupture of several kilometers along the fault.Some of the major faults in the San Andreas Fault system include the Hayward, Calaveras, SanGregorio Fault, Rodgers Creek and Maacama faults. Many of these faults (in particular the SanAndreas and Rodgers Creek Faults) have been seismically active in historical time and haveproduced large earthquakes. Figure 4 shows the fault map of the Bay Area.3.1.1 Historic SeismicityThe Bay Area has experienced at least nineteen earthquakes greater than Magnitude 1 6.0 duringthe last 150 years the largest of these has been the April 21, 1906 Great San Franciscoearthquake. [25] The Magnitude 7.8, 1906 earthquake caused extensive damage in the SanFrancisco Bay Area including Sonoma County. Other significant historic earthquakes thatcaused substantial damage in the Bay Area include the 1838 earthquake, the 1868 earthquake onthe Hayward Fault and the recent Loma Prieta earthquake in 1989.For the Bay Area, a plot of moderate to large earthquakes on a time scale (Figure 5) shows thatthe seismic activity in the region prior to the 1906 earthquake to be significantly higher than thatfollowing it. Most likely, this is because the 1906 earthquake created a stress shadow bysubstantially relaxing stress on all of the Bay Area faults that form the San Andreas Faultsystem. [26] As shown in Figure 5 there appears to be an increased earthquake activity in the lasttwo decades suggesting that the Bay Area might be emerging from the 1906-induced stressshadow, and that faults that have been quiescent during the past century, may now once againbecome more seismically active.Recent work by the Working Group on California Earthquake Probabilities (WGCEP), a groupof leading scientists, practitioners and academicians has estimated very high probabilities (67%)1 Magnitude is a quantitative measure of energy released in an earthquake. Due to the logarithmic nature of the magnitude scale, an increase in magnitude by one unitproduces 30 times more energy. A qualitative descriptor of the effects of earthquake on the built environment or those experienced by humans is the ModifiedMercalli Intensity. It ranges from I (not felt) to XII (complete destruction) with intermediate values such as VI described as felt by everyone, many frightened and runoutdoors or IX described as general panic, complete destruction of poorly constructed masonry.12 Sonoma County Water Agnecy.doc

of a major earthquake in the Bay Area in the next 30 years (Figure 6). The most significantcontributors to this probability are the Hayward and the Rodgers Creek faults, the latter runsthrough the Agency’s service area and cuts across one of its major pipelines (Figure 7). TheWGCEP has estimated an 18% probability for a major earthquake on the Rodgers Creek faultand 27% for the Hayward-Rodgers Creek fault system. The probability for these faults is evenhigher than the probability of a major earthquake on the San Andreas Fault.The most recent earthquakes on the Rodgers Creek fault include the October 1, 1969 M 5.6 and5.7 earthquakes near Santa Rosa. [27-30] The earthquakes occurred within a span of about 2.5hours and resulted in considerable damage in Santa Rosa including significant damage to waterdistribution system including cracks in the Lake Ralphine Dam. Prior to the 1969 events, theother known earthquake on the fault consists of the 1898 Mare Island event with an estimatedmagnitude between 6.2 and 6.7. It is estimated that for the portion of the fault located in theAgency’s service area the average earthquake recurrence interval is on the order of 131-370years. [31-33]3.1.2 Surface Fault Rupture HazardIn large magnitude earthquakes fault rupture can extend to the ground surface resulting in oneside of the fault moving relative to the other by as much as several feet. Structures locatedwithin the fault rupture zone are subjected to excessive ground deformations. Most structuresare not designed to withstand such large deformations and experience major damage.From the surface fault rupture hazard viewpoint, the Agency’s facilities are most severelyimpacted by the Rodgers Creek Fault, which passes through the Agency’s service area and cutsacross the Santa Rosa aqueduct near Doyle Park in the City of Santa Rosa. Paleoseismicobservations on the Rodgers Creek fault show the occurrence of three surface-rupturingearthquakes between about AD 1000 and 1776 with approximately 5.1 to 7.2 m of offset. TheCDMG Special Publication 112, the Planning Scenario for a major earthquake on the RodgersCreek fault prepared by the California Geological Survey [34] considers a Magnitude 7.0earthquake with an average offset of 3 feet as most likely. Surface displacements on this order ofmagnitude are almost certain to rupture the Santa Rosa aqueduct, which is not designed towithstand such large displacements.In addition to the Rodgers Creek fault, recent studies by the USGS suggest that the BennettValley Fault, a fault previously considered inactive may be an active structure. This fault islocated in the step over region between Rodgers Creek and Maacama fault and transfers slipacross the two faults (Figure 7). Mapping of the Bennett Valley fault in the Spring Lake areashows that the fault crosses the Sonoma aqueduct and the Oakmont pipeline near the Sonoma13 Sonoma County Water Agnecy.doc

ooster stations. The fault is well expressed in this area and crosses beneath the Sonoma BoosterStation No. 2. The amount of possible lateral slip and/or vertical offset across the mapped faulttraces is currently unknown but the inferred high slip rate [35] suggests a correspondingly highpotential for surface fault rupture.3.1.3 Strong Ground ShakingSeismic waves generated as a result of fault rupture propagate through the earth’s crust from therupture front and cause strong shaking of the ground. The intensity of ground shaking at aparticular location is measured in terms of ground acceleration, which generally decreases withdistance from the earthquake source unless modified by local subsurface conditions. Themaximum acceleration recorded at a site is referred to as the peak ground acceleration (PGA)and is reported as a fraction of earth’s gravitational acceleration (g). The total force experiencedby a structure can be related directly to the level of acceleration it experiences.The distance of the Agency’s facilities from the nearest major Bay Area faults is shown in Table1. The table also shows the expected PGA at each of the Agency’s facilities from a maximumearthquake on these faults. In addition, the table also lists the PGA values estimated by theUnited States Geological Survey (USGS) for a 10% probability of exceedence in 50 years (meanreturn period of 475 years). This probability level is typically used in seismic design ofstructures and forms the basis of the 1997 Uniform Building Code (UBC). The table shows thatthe estimated median PGA values at the Agency’s facilities range between 0.3g to 0.8g. Figure 8shows the Agency’s system together with a plot of USGS estimates of PGA contours in SonomaCounty. Because of their proximity to the Rodgers Creek fault, the Kawana and Ralphine tanksand the Sonoma booster station have the highest predicted ground motions.14 Sonoma County Water Agnecy.doc

Table 1Peak Ground Acceleration (g) at Agency’s FacilitiesNameDistance to Deterministic (M = 7) Probabilistic 500Fault (km) Median Median + σYearDiversion Facilities 10.9 0.29 0.44 0.40Occidental Road Well 9.8 0.38 0.58 0.42Sebastopol Road Well 9.8 0.38 0.58 0.42Todd Road Well 9.1 0.40 0.61 0.42Ralphine Tanks 3.3 0.67 1.03 0.57Cotati Tanks 8.8 0.41 0.63 0.46Forestville Tank 11.4 0.33 0.51 0.40Annadel No. 1 Tank 6.4 0.51 0.78 0.46Annadel No. 2 Tank 8.3 0.43 0.66 0.46Eldridge Tanks 8.5 0.42 0.65 0.41Sonoma Tanks 7.0 0.48 0.74 0.42Kastania Tank 7.8 0.45 0.69 0.51Kawana Springs Tank 1.0 0.77 1.19 0.54Forestville Booster Station 11.4 0.33 0.51 0.40Sonoma Booster Station 4.1 0.63 0.96 0.57Ely Booster Station 6.8 0.49 0.75 0.53Eldridge Booster Station 8.5 0.42 0.65 0.41Wilfred Booster Station 5.5 0.55 0.85 0.51Kastania Booster Station 7.8 0.45 0.69 0.51Kawana Booster Station 6.9 0.48 0.75 0.48River Road Chlorination Facility 11.4 0.33 0.51 0.40Mirabel Chlorination Facility 12.0 0.32 0.49 0.40Wohler Chlorination and Corrosion Control Facility 10.0 0.37 0.57 0.40Note: The peak ground acceleration values are for rock conditionsDeterministic ground motions were computed using the Abrahamson and Silva attenuation relationship [36]Probabilistic ground motions computed by USGS were based on an average of multiple attenuation equations including theAbrahamson and Silva3.1.4 Liquefaction and Lateral SpreadLiquefaction is a phenomenon in which loose granular soils saturated with water lose their abilityto carry load when subjected to strong shaking. The shaking causes an increase in pressureexerted by the entrapped water within the pores of soil matrix and causes the soil to flow as aliquid. This subsurface process manifests itself in the form of large ground deformation and sandvolcanoes at the ground surface. When liquefaction occurs near a free face such as a stream orriver bank large horizontal movement of ground can occur as the overlying soil layers slide overthe liquefied layer towards the free face. This phenomenon known as lateral spread is verydetrimental to buried pipelines and pose a much greater hazard to facilities and pipelines thanliquefaction alone [37,38] . Lateral spreads can develop on gentle slopes (less than 3 degrees) andmay produce horizontal displacements of as much as tens of feet. [39]The potential for liquefaction depends on both the susceptibility of a soil deposit to liquefy aswell as the opportunity for ground motions to exceed a specified threshold level. Given theproximity of Sonoma County to the San Andreas and Rodgers Creek faults, virtually all parts of15 Sonoma County Water Agnecy.doc

the County are exposed to long duration peak ground accelerations in excess of 0.15g (Figure 8).To assess the liquefaction and lateral spread hazard to the Agency’s facilities, potentiallyliquefiable soils that consist of young alluvial deposits and artificial fill present within theAgency’s service area are overlain on the Agency’s water supply system as shown in Figure 9.The figure also shows locations where the pipelines cross streams and open slope faces. Suchstream crossing locations coupled with high liquefaction potential have a very high likelihood oflateral spread and resulting pipeline damage.All of the Agency facilities that lie in areas marked as moderate, high and very high will likelyexperience liquefaction because the estimated ground acceleration at all Agency facilities isgreater than 0.3g, the triggering threshold for a moderate susceptibility rating. As shown inFigure 9, significant portions of the Agency’s system are vulnerable to liquefaction. Areas ofhigh and very high liquefaction potential exist at collector sites, Mirabel well-field and Elybooster station. A high susceptibility to liquefaction exists along the transmission lines, theWohler Intertie, most of the Santa Rosa aqueduct, significant portions of Petalumaaqueduct and localized areas of the Cotati and Sonoma aqueduct. Creek crossings alongthese portions of the transmission lines, as shown in Figure 9, have a very high potential fordamage due to the potential for lateral spread. The main power line from the Wohlersubstation to the collectors is also located in an area of very high liquefaction potential.3.1.5 Earthquake Induced LandslidesEarthquake-induced slope failures or landslides commonly occur over wide areas on hill slopesduring large (magnitude 6.5 or larger) earthquakes and can produce significant damage. Themost common earthquake-induced failures are rockfalls, rock and soil slides, and soilavalanches, slumps and flows. Rockfalls, avalanches, and flow-type failures are especiallyhazardous because they often occur rapidly and travel great distances from the point of initiation.These types of rapid failures present significant impact to structures sited on slopes or valleyareas downhill from the initiation site, and can distort or break shallow-buried pipelines crossingthe sliding plane of the slope failure.The opportunity for seismically induced slope failure is dependent on the potential forappropriately high levels of ground shaking to initiate movement. The susceptibility for failureis based on conditions that predispose the slope to failure including static stability, local geology,slope inclination, groundwater conditions, rock strength, and the duration and intensity ofshaking. The potential for landslides is higher during seasonal wet periods when hill slopes aresaturated with water.16 Sonoma County Water Agnecy.doc

Figure 10 shows the USGS regional landslide hazard mapping for Sonoma County. Thoughvarious workers have mapped the geology of the study area, most published geologic maps of theAgency’s service area do not delineate active or recently active landslides or slope failures.Therefore, there is a possibility of small localized landslides that could result in damage topipelines especially along the runs that connect to the tanks located on hills.Figure 10 shows that most of the Agency’s water system is located outside of activelandslide areas with only a few locations such as a portion of the Santa Rosa aqueduct nearthe collectors, a small potion of the Russian River-Cotati Intertie south of Forestville tanksand areas near the Kastania, Eldridge, Cotati and Annadel No. 2 tanks may be somewhatsusceptible to landslide hazard. However, more detailed assessments show that thelandslide hazard at these locations is low.3.2 FLOOD HAZARDFlooding is defined as the overflow of excess water from a water body onto adjacent floodplainlands. Flooding typically results from large-scale weather systems generating prolonged rainfallor on-shore winds. Other causes of flooding include locally intense thunderstorms, snowmelts,ice jams and dam failures. Floods are capable of undermining buildings and bridges, erodingshorelines and riverbanks, tearing out trees, washing out access routes, and causing loss of lifeand injuries.Flash floods pose more significant safety risks than other riverine floods because of the rapidonset, the high velocity of water, the potential for channel scour, debris load and increase inturbidity of water that can directly impact the Agency’s water supply. In addition, more than oneflood crest may result from a series of fast moving storms.Sonoma County has had significant flooding in the past and is expected to have floods in thefuture. Table 2 shows the highest recorded flood levels between 1955 and 1996 at the HaciendaBridge on the Russian River. Flood water getting as high as approximately 15 feet above theflood level (34 feet) has occurred in the past.17 Sonoma County Water Agnecy.doc

Table 2Historic Floods in Sonoma CountyNo.DateWater Level at HaciendaBridge (feet)1 February 18, 1986 48.562 January 9-10, 1995 48.013 December 23, 1955 46.954 December 23, 1964 46.855 January 1, 1997 45.106 January 5, 1966 42.537 March 10, 1995 42.248 January 27, 1983 41.639 January 24, 1970 41.2010 February 1, 1963 40.95Flood level at Hacienda Bridge = 34 feetFigure 11 shows the flood hazard within the Agency’s service area prepared by the FederalEmergency Management Agency (FEMA). These maps use computed or estimated watersurface elevations combined with topographic mapping data to represent the flood hazard. The100-year flood represents a compromise between minor floods and the greatest flood likely tooccur in a given area. In most cases the 100 year flood is less than the flood of record and hasbeen widely adopted as the common design and regulatory standard in the US. It was formallyestablished as a standard for use by Federal agencies in 1977 and later confirmed by FEMA in1982.Figure 11 shows the Agency’s system overlain on the FEMA flood maps. The figure also showsthe locations where the pipelines cross creeks. These locations together with areas of high floodhazard are at the highest risk of damage due to channel scour. Debris flow in streams and thepotential for bottom scour and the resulting pipeline damage is also a potential hazard. Asshown in the figure, the Agency facilities with the highest risk of flooding include thoselocated in the Mirabel and Wohler area, Ely booster station, the Sebastopol and ToddRoad wells, significant sections of the Russian River-Cotati Intertie, Forestville aqueductand Wohler Intertie and some portions of the Santa Rosa aqueduct. Stream crossinglocations of the transmission lines located in the areas of high flood hazard are mostvulnerable to damage due to flood related scour. In addition, there are three locationswhere a pipeline is suspended from a bridge at the stream crossing location. At theselocations, the pipeline is vulnerable to damage by impact from floating debris.18 Sonoma County Water Agnecy.doc

3.3 GEO-HAZARDS3.3.1 LandslidesHillslopes along the Agency’s pipeline corridors and their facilities have been modified by masswasting processes, including landslides, debris flows, soil creep, gully and stream erosion, andsheet wash. These processes are episodic, with failures typically occurring during or shortlyafter periods of heavy precipitation. Types of slope failure that are usually caused by prolongedrainfall include rotational slumps, earthflows, and rapidly moving debris flows. Figure 12 showshistoric landslides in Sonoma County during El Nino storms of 1997-1998.Most of the landslides present along the Agency’s pipeline corridors fall into two primary types:(1) rotational and translational landslides involving bedrock and colluvium, and (2) debris orearth flows involving colluvium.Rotational and translational landslides pose the primary slope stability hazard along the pipelinecorridors. The landslides commonly are distinguished by vegetation changes and characteristicslope morphology, including undulating, hummocky ground surface. Deep rotational andtranslational landslides typically involve underlying bedrock and are mainly associated withsteep slopes greater than 15˚ and showing signs of water seepage. As shown in Figure 10 theoverall landslide hazard within the Agency’s water system is low.Debris and/or earthflows typically occur where colluvium collects in topographic swales onhillslopes. During heavy rainfall, saturated colluvium may flow rapidly down drainage channels.Poorly sorted debris within a flow may be deposited where the slope angle decreases or mayincrease in volume with distance traveled downslope. The primary potential hazard posed bydebris flows to the pipeline is the relatively rapid movement of soil surrounding the pipeline, andassociated displacement of the pipeline. Pipeline displacement is more likely at the debris-flowheadscarp than in lower parts of a debris flow. Figure 13 shows debris flow hazard in SonomaCounty mapped by the USGS. Because debris flow travels downslope and downstream from thesource area, the hazard associated with debris flow extends beyond the mapped areas. The mapalso shows debris-flow sources (represented by black dots on the map) mapped after the majorstorms of January 1992.3.3.2 Corrosive SoilsPotential external corrosion hazards to pipeline systems are dependent in part on the conductivityof the ground and the corrosive nature of soils in which the pipeline is buried. Corrosivity ofsoils is dependent on soil texture, soil pH, moisture content, and geochemical composition of19 Sonoma County Water Agnecy.doc

fluids within the soil. These factors, in turn, are influenced by the physical and mineralogiccomposition of soils. Soil composition often is directly derived from the characteristics of theunderlying geologic deposits on which they develop. Silty and clayey soils tend to have thehighest corrosion potential in contrast with granular soils (sands and gravels). In addition, thetopography of the land, depth to groundwater, and native vegetation all influence the soilcorrosivity potential.Although soil corrosivity can exist within a broad range of soil conditions, the extent of acidityor alkalinity of a soil, as expressed by pH, directly influences corrosion susceptibility. Soil withpH generally less than 9.0 has been found to be among the more corrosive types. Typically soilswith a pH of 0.0 to 4.0 are acidic and, where saturated, can serve as a corrosive electrolyte. Soilswith a near neutral pH of 6.5 to 7.5 and low Redox conditions are optimum for sulfate reductionby bacteria, which can cause localized corrosion.Soil resistivity also has a strong influence on the corrosion rate. Generally, the higher theresistivity of the soil, the lower is its corrosion rate. Soil resistivity arises from a number offactors, but fine-grained soils (silts and clays) typically have the lowest resistivities and thus thegreatest corrosion susceptibility.The distribution and type of soils within the Agency’s service areas were digitized fromDepartment of Agriculture Soil Conservation Service (SCS) county soil report. Soils aregenerally sampled only to a depth of 5 to 6 feet (most pipelines are buried within this zone);therefore, soil descriptions are limited to that depth and may not be representative of deeper soilconditions. Soil surveys typically generalize soil properties and thus soil corrosivity estimateslikely are conservative. In the SCS report, soil unit codes were referenced to the shrink-swelland corrosivity engineering properties and the corrosion potential as Low, Medium, or High.Corrosivity values compiled from SCS soil surveys, although unitless, are calculated by the SCSbased on the rate uncoated steel and concrete might corrode when buried in a soil. These indexvalues are derived from soil texture, drainage, acidity, and electrical conductivity data. Bothsets of values are depicted in the soil corrosion maps for the Agency’s service area as shown inFigure 14 and Figure 15. The figures show that except for the Sonoma aqueduct, which hasa limited exposure to corrosive soils, all of the Agency’s aqueducts lie in highly corrosivesoils. The Agency has an active corrosion control program, and as a result there are noindications of prevalent corrosion related damage to the transmission system. TheAgency’s corrosion control program consists of maintaining cathodic protection systems onall of its aqueducts. These systems employ either impressed current or sacrificial anodes.The Agency has an anode testing program that ensures that anodes are replaced as they20 Sonoma County Water Agnecy.doc

are consumed by the system. No mitigation measures were identified in the planningprocess due to the Agency’s on-going maintenance program.3.4 FIRE HAZARDFire is relevant to the Agency’s system from two perspectives: (a) potential damage that firesmay directly cause to the Agency’s facilities, and (b) fire fighting demands on the Agency’ssystem – that is, the emergency water supply needs of fire departments who may be relying onthe Agency to supply that water. Both aspects are driven by the fire hazard in Sonoma County.Periodic fires are part of the natural environment and consist of four categories that includewildland fires, urban-wildland interface fires, firestorms and prescribed fires. Wildfires arefueled by naturally occurring trees, brush and grasses; the urban-wildland interface fires arefueled by vegetation and built environment; firestorms occur during extreme weather andgenerally burn until conditions change or the available fuel is exhausted and; prescribed fires arecontrolled burns intentionally set for fire management.The behavior of wildfires is impacted by three principal factors that include topography, fuel andweather. Topography is important because the movement of air over the terrain tends to direct afire’s course and gulches and canyons can funnel air and act as a chimney. Saddles andridgetops tend to offer lower resistance to the passage of air and will draw fires. Water tanks,which are usually located on ridgetops are, therefore, susceptible to fire with south facing slopesbeing more susceptible because they receive higher solar radiation. Steeper uphill slopes tend toincrease the rate of spread, whereas downhill slopes tend to slow down the rate of spread.Fuel for fires is provided by the amount of vegetative material available. Different fuels havedifferent burn qualities. For example grasses, release little energy but can sustain very high ratesof spread. Moisture and continuity of fuel is also very important for the spread of fire.Figure 16 shows the fire threat map in Sonoma County prepared by the California Department ofForestry. The map shows five threat classes that range from no threat to extreme threat. Thefigure shows that most of the Agency’s water system is in an area of low fire hazard except forthe facilities in the Wohler and Mirabel area. The figure also shows a high fire threat near theAnnadel No. 2 tank. However, a more detail examination during the site reconnaissanceconfirmed a low fire hazard because of a clearing zone around the facilities. The Agency has anactive maintenance program to address such issues. Furthermore, since the Agency is awholesaler it does not have direct responsibility for fire fighting.21 Sonoma County Water Agnecy.doc

Table 3 shows some of the major fires in Sonoma County that burned over 1,000 acres. Theburn area of these fires is shown in Figure 17. The figure shows that none of these historic fireshave impacted the Agency’s service area.22 Sonoma County Water Agnecy.doc

Table 3Major Historic Fires in Sonoma CountyDateLocationAcresBurnedSeries: Hanly, Mt. George, Nunns Canyon in Napa and Sonoma County 71,500Sep-64 Hanly (Sonoma County) 52,700Nunns Canyon (Sonoma County) 10,400Series of nine fires in Glenn, Napa and Sonoma County 113,766Knight's Valley (Sonoma County) 6,000Pocket Ranch (Sonoma County) 4,0001965Arrowhead (Sonoma County) 4,000Chileno Valley (Sonoma County) 5,000Pressley (Sonoma County) 5,500Coleman Valley (Sonoma County) 1,500Austin Creek (Sonoma County) 7,0001972 Bradford 1,760Aug-78 Creighton Ridge 11,405Aug-88 Cloverdale 1,833Sep-88 Geysers 9,000Aug-96 Cavedale 2,100Oct-99 Geyser Road 1,300Jun-00 Berryessa (Napa and Sonoma) 5,731Sep-04 Geysers (Sonoma and Lake) 12,525Because of the wholesale nature of the Agency’s transmission system, the Agency does not havea direct responsibility to provide fire water, except for a very limited number of fire hydrantslocated along the Agency’s aqueducts.3.5 DROUGHTUnlike typical natural disasters such as earthquakes, floods or fires, drought occurs graduallyover a multi-year period. One dry year does not normally constitute a drought in California. Forexample the driest single year of California's measured hydrologic record was 1977. California's[40, 41]most recent multi-year statewide drought was 1987-1992. The Agency’s extensive systemof water supply infrastructure -- its reservoirs, groundwater basins, and inter-regionalconveyance facilities -- mitigates the effect of short-term dry periods for most water users in itsservice area.Defining when a drought begins is a function of drought impacts to water users and therefore,there is no universal definition of when a drought begins or ends. Impacts of drought aretypically felt first by those most reliant on annual rainfall -- ranchers engaged in dryland grazing,rural residents relying on wells in low-yield rock formations, or small water systems lacking areliable source. Drought impacts increase with the length of a drought, as carry-over supplies inreservoirs are depleted and water levels in groundwater basins decline.The historical record of California hydrology is brief in comparison to the time period ofgeologically modern climatic conditions. As a result, measured hydrologic data for droughts23 Sonoma County Water Agnecy.doc

prior to 1900 are minimal. Multi-year dry periods in the second half of the 19th century can bequalitatively identified from the limited records available combined with historical accounts butthe severity of the dry periods cannot be directly quantified. Paleoclimatology data based on treering studies suggest sustained drought throughout much of the continental U.S. during the mid-1500s that may have lasted as long as 50 years. In addition, some climate researchers describe a“Medieval Megadrought” to describe a series of long duration droughts in the Western U.S.during the 900 to 1400 A.D. time period. Researchers identified two epic drought periods fromthese remains, one lasting more than two centuries prior to A.D. 1112, and the other lasting morethan 140 years prior to 1350.Droughts, in California within the recorded history, that span over several years include: 1912-1913, 1918-1920, 1923-1924, 1929-1934, 1947-1950, 1959-1961, 1976-1977, and 1987-1992.The criteria commonly used in designing storage capacity and yield of large Northern Californiareservoirs was established as a result of the 1929-1934 drought. The 1987-1992 drought wasnotable for its six-year duration and the statewide nature of its impacts. However, droughtsexceeding three years are relatively rare in Northern California, the source of much ofCalifornia's developed water supply.In the 1987-1992 drought, water users served by most of the State’s larger suppliers did notbegin to experience shortages until the third or fourth years of the drought. Reservoir storageprovided a buffer against drought impacts during the initial years of the drought. During thistime period groundwater extraction increased substantially and wells or springs serving severalsmall water systems in the Russian River corridor went dry such that water haulage becamenecessary.Droughts can have a significant impact on society that can include lost jobs and revenues in thelandscaping and nursery industries, unemployment and other socioeconomic impacts in farmingdependent regions, increased risk of wildfire, additional cost for homeowners to replace lawnsand landscaping, loss of forests, decline in fish population, lost revenues to water basedrecreation businesses and reduced hydroelectric power generation. Droughts result in a declineof revenues and an increase in operational costs for water agencies. The former occurs due tovoluntary or mandatory reductions in water use and the later due to additional cost of purchasingwater, deepening wells, or implementing water education and conservation campaigns.It is not easy to predict droughts because climate is inherently variable and predicting droughtdepends on the ability to forecast two fundamental meteorological surface parameters,precipitation and temperature. Anomalies of precipitation and temperature may last from severalmonths to several decades and how long they last depends on many factors such as air–seainteractions, soil moisture and land surface processes. Generally, the immediate cause of24 Sonoma County Water Agnecy.doc

drought is the predominant sinking motion of air (subsidence) that results in compressionalwarming or high pressure, which inhibits cloud formation and results in lower relative humidityand less precipitation. Much of California enjoys a Mediterranean-like climate with cool, wetwinters and warm, dry summers. An atmospheric high pressure belt results in fair weather formuch of the year, with little precipitation during the summer. The high pressure belt shiftssouthward during the winter, placing the State under the influence of Pacific storms bringing rainand snow. Most of California’s moisture originates in the Pacific Ocean. As moisture-laden airmoves over mountain barriers such as the Sierra Nevada, the air is lifted and cooled, droppingrain or snow on the western slopes. This orographic precipitation is important for the State’swater supply. The majority of California’s groundwater production occurs from alluvialmaterials in the large basins. Groundwater levels in such basins typically decline during droughtsdue to increased extractions.The fundamental drought impact to water agencies is a reduction in available water supplies. Asa result, historic occurrences of drought have encouraged water agencies to review the reliabilityof their water supplies and to initiate planning programs addressing identified needs forimprovement. In addition, public and media interest in droughts fosters heightened awareness ofwater supply reliability issues in the Legislature. More than 50 drought-related legislativeproposals were introduced during the severe, but brief 1976-77 drought. About one-third of theseeventually became law. Similar activity on drought-related legislative proposals was observedduring the 1987-92 drought. One of the most significant pieces of legislation was the 1991amendment to the Urban Water Management and Planning Act, in effect since 1983, whichrequires water suppliers to estimate available water supplies at the end of one, two, and threeyears, and to develop contingency plans for shortages of up to 50 percent. The Sonoma CountyWater Agency’s 2005 Urban Water Management Plan (SCWA, 2006) presents water supply todemand comparisons through 2030. The plan also presents water supply to demand comparisonsfor single dry to multiple dry year scenarios. The comparisons show that the Agency hasadequate supply through 2030. For dry years, water demands exceed supply starting in 2020 butthe Agency has developed plans to work with its contractors to reduce demands.3.6 OTHER HAZARDSTable 4 shows major weather related events in Sonoma County. Description for some of themost significant weather related hazards is provided in the following sections.25 Sonoma County Water Agnecy.doc

Table 4Historic Weather Related Hazards in Sonoma CountyHazard Date Time Magnitude Deaths InjuriesProperty CropDamage DamageBlowing DustNovember 2, 1994 5:21 AM N/A 0 0 0 0November 10, 1994 10:43 PM N/A 0 0 0 0December 2, 1994 11:22 AM N/A 0 0 0 0December 3, 1994 1:20 PM N/A 0 0 0 0Dense FogDecember 8, 1994 12:45 PM N/A 0 0 0 0December 9, 1994 5:04 PM N/A 0 0 0 0December 10, 1994 6:18 AM N/A 0 0 0 0Excessive HeatAugust 15, 1996 4:00 PM N/A 4 0 0 0June 14, 2000 12:00 PM N/A 9 102 0 0February 4, 1996 10:00 AM N/A 0 0 0 0February 2, 1998 6:50 PM N/A 0 0 $2.0M 0February 3, 1998 4:00 AM N/A 0 0 $5.0M 0February 3, 1998 9:30 AM N/A 0 1 $200K $159KFebruary 5, 1998 6:00 PM N/A 0 0 0 0February 6, 1998 12:22 PM N/A 0 0 0 0February 7, 1998 1:18 PM N/A 0 0 0 0Flash FloodFebruary 13, 2000 9:00 PM N/A 0 0 0 0January 20, 1993 7:15 AM N/A 0 0 $500K 0March 9, 1995 10:34 AM N/A 0 0 $3.5M $0.5MDecember 31, 1996 7:00 PM N/A 1 0 0 0January 3, 1997 8:00 PM N/A 1 0 0 0February 13, 2000 10:00 AM N/A 0 0 0 0January 11, 2001 10:00 AM N/A 0 0 $7.0M 0December 16, 2002 2:00 AM N/A 0 0 0 0Hail December 9, 2003 11:15 PM 0.75 in. 0 0 0 0December 12, 1995 2:45 AM N/A 0 0 0 0December 29, 1996 12:00 AM N/A 0 0 0 0Heavy RainJanuary 2, 1998 4:00 AM N/A 0 1 0 0January 1, 2002 3:00 AM N/A 0 0 $200K 0December 15, 2002 8:00 PM N/A 0 0 0 0Heavy Snow February 11, 2001 8:00 AM N/A 0 0 0 0July 16, 1996 3:30 PM 35 kts. 1 0 0 0November 29, 1998 10:00 PM 75 kts. 0 0 $1.8M 0February 9, 1999 11:00 AM 60 kts. 0 0 $1.0M 0April 3, 1999 8:00 AM 85 kts. 1 2 0 0February 13, 2000 10:00 AM 0 kts. 0 0 $250K 0March 19, 2000 3:10 PM 72 kts. 0 0 $250K 0High WindOctober 21, 2000 9:45 PM 97 kts. 0 1 0 0March 4, 2001 10:54 AM 71 kts. 0 0 $2.7M 0November 24, 2001 7:00 AM 85 kts. 0 0 $7.1M 0November 7, 2002 4:00 PM 100 kts. 0 0 $1.0M 0December 30, 2002 11:21 PM 63 kts. 0 0 $600K 0December 14, 2003 4:33 AM 61 kts. 0 0 0 0February 25, 2004 8:29 AM 58 kts. 0 0 0 0February 4, 1993 9:00 PM 0 kts. 0 0 $500K 0Lightining January 25, 2001 12:00 PM N/A 0 1 $1.0M 0Storm Surge February 25, 2004 10:00 AM N/A 0 0 0 0June 1, 1958 7:55 AM F2 0 0 $25K 0February 17, 1959 6:45 AM F 0 0 $3K 0November 10, 1964 3:34 AM F 0 0 $3K 0February 27, 1983 7:20 AM F1 0 0 $25K 0TornadoDecember 2, 1992 5:00 PM F1 0 0 $25K 0December 2, 1992 5:00 PM F1 0 0 $25K 0December 2, 1992 5:00 PM F1 0 0 $250K 0February 22, 1996 1:00 AM F1 0 0 0 0December 23, 1996 11:30 AM F0 0 1 $1K 1KDecember 5, 1998 6:20 PM F1 0 0 $1.0M 0February 16, 1994 8:00 PM N/A 0 0 $500K 0Winter StormDecember 9, 1995 10:00 AM N/A 1 15 $60.0M 5.0MMarch 10, 1995 5:09 AM N/A 0 0 0 026 Sonoma County Water Agnecy.doc

3.6.1 TornadoesWhile California does have tornadoes, it is relatively low-risk compared to states in theMidwestern and Southern United States as shown in Figure 18. [42]Since 1950, 292 tornadoes have occurred in 42 counties in California, resulting in 103 injuries.However, no deaths have occurred, and none of the California tornadoes since 1950 have beenover F2 on the Fujita Scale (see Table 5). Of these 292 tornadoes, only eight percent reached F2,whereas 53 percent were at F0, the least severe type and 39 percent reached F1. No majortornadoes (those of F3-F6) have occurred after 1880 in California. The biggest risks of tornadoesin California include light to moderate damage to homes, destruction of mobile homes, andinjuries caused by light object projectiles during F2 scale tornadoes. In the 52 years between1950 and 2002, the average occurrence of an F2 scale tornado has been approximately onceevery 2.36 years. [43] Table 5Fujita Scale for Tornado IntensityScale ValueF0F1F2F3F4F5Wind Speed Range and Description of Damage40-72 mph (17.8-32.6 m/s): Light damage. Some damage to chimneys; tree brances broken off;shallow-rooted trees pushed over; sign boards damaged. Average number per year, 1953-1989: 218(29 percent).73-112 mph (32.7-50.3 m/s): Moderate damage. The lower limit is the beginning of hurricane windspeed. Roof surfaces peeled off; mobile homes pushed off foundation or overturned; moving autospushed off road. Average number per year, 1953-1989: 301 (40 percent).113-157 mph (50.4-70.3 m/s): Considerable damage. Roof torn out from houses; mobile homesdemolished; boxcars pushed over; large trees snapped or uprooted; light-object missiles generated.Average number per year, 1953-1989: 175 (23 percent).158-206 mph (70.4-91.9 m/s): Severe damage. Roofs and some walls torn off well-constructedhouses; trains overturned; most trees in forest uprooted; heavy cars lifted off ground and thrown.Average number per year, 1953-1989: 43 (6 percent).207-260 mph (92.0-116.6 m/s): Devastating damage. Well constructed houses leveled; structureswith weak foundations blown off some distance; cars thrown; large missiles generated. Averagenumber per year, 1953-1989: 10 (1 percent).261-318 mph (116.7-142.5 m/s): Incredible damage. Strong frame houses lifted off foundations andcarried considerable distances to disintegrate; automobile-sized missiles fly through the air in excessof 100 yards; trees debarked. Average number per year, 1953-1989: 1 (0.002 percent).* Wind speeds in the range are defined by Fujita to be "the fastest 1/4-mile wind"Source: Golden and Snow, "1991: NOAA, NWS Disaster Survey Report", 19913.6.2 Hurricanes and Other Weather Related HazardsCalifornia is also at very low risk of hurricanes, although it is possible for one to threaten thesouthern California coast. [44] No hurricanes have hit California in recorded history becausetropical storm winds generally blow from east to west, however, the State is affected by heavyrain resulting from tropical winds that blow north from Mexico and become colder by the timethey hit California. [45]27 Sonoma County Water Agnecy.doc

Risk to the Agency’s facilities from tornadoes or a hurricane is low compared toearthquakes and flood because any damage will be localized and not likely to be systemwide. Therefore, it would be possible to respond in a timely manner to repair the damagewith small downtime. The most vulnerable system components to tornados, hurricanes,high wind and lightning strike will be the power and SCADA systems. The Agency has theability to operate its system from three locations that include the College Avenue facility,the Sonoma Valley County Sanitation District (SVCSD) reclamation plant and the RussianRiver County Sanitation District (RRCSD) treatment facility. In the event the CollegeAvenue facility is nonfunctional, radio communications to the other two locations mostlikely cannot be maintained. The Agency is currently in the early planning stages of settingup a mobile command center for their SCADA system.3.7 HAZARDS SUMMARYTable 6 provides a hazards summary for the Sonoma County Water Agency.Table 6Hazards Summary for Sonoma County Water AgencyHazards History Frequency Probability Impact CommentsNatural HazardsAvalanche No Low Low No Snow uncommonCoastal Erosion Yes Low Low No No infrastructure near coastCoastal Storm Yes Low Low No No infrastructure near coastCorrosive Soils Yes Medium Medium Yes Active corrosion control programDense Fog Yes Low Low Low Limited impactEarthquake Yes Low High High Included in the planExpansive Soils No Low Low Low Uncommon in Sonoma CountyExtreme Heat Yes Low Low Low Short duration eventFlood Yes High High High Included in the planHailstorm Yes Low Low Low Limited impactHurricane No Low Low Low Limited impactLand Subsidence Yes Low Low High Part of earthquake hazardLandslide Yes Medium Medium Low Facilities located outside of hazard areaSevere Winter Storm Yes Medium Medium High Included in the plan as part of floodTornado Yes Low Low Low Low hazard, limited impactTsunami No Low Low Low Facilities located outside of hazard areaVolcano No Low Low Low No active volcanoesWildfire Yes High High Low Facilities located outside of hazard areaWindstorm Yes Low Low Low Limited impactAgricultural HazardsDrought Yes Low Low Med. Part of urban water management planFreeze Yes Low Low Low Limited impactPest Yes Low Low Low No impact to the AgencySalmon Fishing Yes Low Low Low Private sector economic lossTechnological HazardsDam Failure No Low Low Med. Included in planPower Failure Yes Low Low Low Emergency power at critical locationsHazardous Material Release Yes Medium Low Med. Emergency plans in placePandemic Influenza Yes Low Unknown Low Public health issueRadiological No Low Low Low Limited impactTerrorism/Bioterrorism No Low Unknown Unk. SVA study performed28 Sonoma County Water Agnecy.doc

4.0 VULNERABILITY ASSESSMENTDamage to water supply and wastewater collection systems following a major disaster,especially an earthquake, can lead to significant disruption. This is based on observations fromseveral recent earthquakes such as the 1989 Loma Prieta earthquake, the 1994 Northridgeearthquake and the 1995 Kobe, Japan earthquake. In Kobe water pipelines sustained severedamage with numerous breaks that resulted in lack of service in several communities.Approximately 29,000 people were without water supply for a month following theearthquake [46] . Over 100 fires broke out within minutes after the earthquake. Water forfirefighting was available for only 2 to 3 hours, and subsequently water was available fromtanker trucks only. For several days after the earthquake there were long lines of people waitingfor water and food. Similarly there was significant disruption of water service following theNorthridge earthquake. There was damage at 15 locations in the three transmission systempipelines that bring water from Northern California, at 74 locations in large diameter trunk linesand 1,013 locations in the Los Angeles Department of Water and Power’s (LADWP) distributionpipeline network including damage to tanks and other facilities. Water system damage wasdistributed over approximately 1,200 square kilometers. [47]During the 1989 Loma Prieta earthquake 20 million gallons of raw sewage were reportedlydumped into the Oakland Estuary in a six hour period following the earthquake. Damage tosewage treatment facilities during the 1994 Kobe and the 2004 Chuetsu, Japan earthquakesresulted in release of polluted water to flow directly into public bodies of water. Damageresulted from the lifting of pipes and manholes in zones of liquefaction. Damage to sewagesystems can also create a public health hazard, for through backing up of sewage in homes anduncontrolled release of untreated water.4.1 WATER SUPPLYA vulnerability assessment of the Agency’s water supply facilities was performed through areview of available drawings, site reconnaissance and as needed engineering calculations(ranging from simplified to detailed). The Agency’s water transmission system is shown inFigures 1 and 1a with the most credible hazards overlain shown in Figures 7 through 18. Areview of the overall system shows that portions of the system lack redundancy and a single pipebreak or loss of a single component such as a key pump station can result in significantdisruption. The portions of the system that are especially vulnerable are those that serve theSonoma Valley and the Cotati area. The sections below describe the significant vulnerabilitiesassociated with the identified hazards.29 Sonoma County Water Agnecy.doc

4.1.1 Russian River SystemThe primary source of water for the Agency’s water system is the Russian River that feeds anaquifer beneath and adjacent to the river through the overlying gravel by natural filtration. Themost significant vulnerabilities associated with the river consist of possible contamination andincrease in turbidity associated with major floods, wildfires, debris flow and landslides. Ahazardous material spill from an accident can also result in possible contamination. The effect ofsuch contamination can be minimized, depending upon its extent, by releasing water from theupstream dams and flushing the contaminants. The Agency’s emergency operations planaddresses such events. During a major earthquake there could be a loss of permeability of theaquifer due to liquefaction or dynamic densification of the gravel that can result in compressionor dilation of the aquifer. Significant loss of production capacity during a short time following amajor earthquake can occur, but generally the aquifers tend to recover after a period of time.Such changes have been observed in past earthquakes.The Agency’s Warm Springs and Coyote Valley dams are located within close proximity ofmajor active faults. The dams were constructed in 1982 and 1959, respectively. The WarmSprings dam is located 4 kilometers from the Healdsburg fault, a northward extension of theRodgers Creek fault, and 10 kilometers from the Maacama, 23 kilometers from the Hayward and29 kilometers from the San Andreas Fault. The Coyote Valley dam is located 1.4 kilometersfrom the Maacama fault, and more than 50 kilometers from the San Andreas, Rodgers Creek andHealdsburg faults. Both dams are part of the flood control system, and the US Army Corps ofEngineers is responsible for dam safety. As reported by the Army Corps, the safety assessmentof both dams and appurtenant structures to account for the most recent information on seismicand flood conditions are currently overdue.4.1.2 Diversion FacilitiesThe components of the Agency’s system that facilitate the diversion of water from the source(the Russian River aquifer) to the transmission system are referred to as the diversion facilities.The diversion facilities can be grouped into those that draw water from the aquifer and those thathelp recharge it. The former include the six collector wells and the Mirabel well field, while thelatter include the inflatable dam, the RDS (river diversion system) caisson, infiltration ponds,diversion channels and the main dike.The earliest of the six collector wells were built in 1958 and the latest in 2005. The generalconstruction of the collector well includes a large diameter (ranging from 13 to 18 feet insidediameter and 18 to 33 inch thick walls) concrete caisson that extends from the ground surfaceinto the aquifer. The caissons range in length from about 108 feet to 123 feet. At the bottom of30 Sonoma County Water Agnecy.doc

each caisson, perforated pipes (known as laterals) extend radially into the aquifer. Each lateral isover a 100 feet long and ranges in size from 8 to 10 inch diameter for the older five collectorsand 12 to 18 inches for the newest sixth collector. Each caisson supports a pump house with twopumps that draw water collected inside the caisson. All of the supporting electrical andcommunication systems to operate the pumps remotely are located in the pump house.The pump houses of each collector well are located well above the maximum flood levels andhave a low likelihood of direct damage from flood or debris impact. The diversion systemfacilities are located in an area of very high liquefaction hazard and because of the proximity to afree face of the river bank the collectors are also subject to a very high lateral spread hazard.Structural assessment of the collector wells and the RDS show that three of the sixcollectors and the RDS have a high likelihood of sustaining major damage. Strongearthquake shaking can also cause damage to the electrical and communication equipment that isnot adequately anchored.Other diversion system facilities such as the inflatable dam, the diversion dike, ditches and theinfiltration ponds are also located in an area of high liquefaction and flood hazard. Recentlyportions of the dike were severely damaged due to overtopping of flood waters. The sevenconventional wells of the Mirabel well field are susceptible to flood related debris impact. Theoverall water quality during floods and wild fires is also a concern.4.1.3 AqueductsThe SCWA transmission system consists of 85 miles of aqueducts (pipelines) ranging in sizefrom 16 inches to 54 inches. The system transports water from the Russian River diversionfacilities, located in the Wohler-Mirabel area, southwards and eastwards to the Agency’s servicearea. The transmission system consists of 11 pipeline segments that include the Russian RiverCotati Intertie, the Santa Rosa Aqueduct, the Sonoma Aqueduct, the Petaluma Aqueduct, theOakmont Pipeline, the Wohler-Forestville Pipeline, the Wohler-Mirabel Intertie, the KawanaPipeline, the North Marin Aqueduct, the Collector 6 Pipeline and the Eldridge-MadaronePipeline. The configuration of the Agency’s entire transmission system is shown in Figure 1.The water transmission system is distributed over a large geographical area and traverses zonesof varying geology and topography, and is subject to a range of natural hazards. The system wasbuilt incrementally over a period of several decades (ranging from 1959 to 2003) and under arange of evolving design standards and construction techniques. Pipeline construction consistsof predominantly mortar lined and coated steel pipe and some pre-stressed concrete cylinderpipe. Typical joint types consist of gasket joints, welded bell-and-spigot joints, and welded butt-31 Sonoma County Water Agnecy.doc

strap joints. Most river and stream crossings include concrete encasement over some or most ofthe pipeline between the banks of the river or stream.Major hazards to the pipeline system include earthquakes, floods and landslides, with theearthquakes and earthquake induced hazards such as liquefaction, surface fault rupture, lateralspread and strong ground shaking being the most significant.In general, buried pipelines, such as the SCWA’s aqueducts, are designed for internal pressurewith limited consideration to large relative displacements of ground along its length. Suchpipelines are typically designed with bell and spigot type connections (also known as segmentedpipelines) and do not perform well when subjected to ground failure resulting from earthquakes,floods and landslides. In the 1964 Anchorage, Alaska earthquake more than 100 water pipebreaks were reported. In 1971 San Fernando earthquake, the City of San Fernando temporarilylost water, gas and sewage services due to liquefaction induced lateral spreading along theeastern and western shores of Upper Van Norman reservoir. For relatively small grounddisplacements associated with earthquake ground shaking, the pipelines perform reasonably wellwith certain amounts of random damage that can usually be handled as part of emergency repairsfollowing an earthquake.The Agency’s pipelines cross many locations where they may be subjected to grounddeformation. The most obvious location is the Rodgers Creek fault crossing of the Santa Rosaaqueduct. Surface fault rupture displacement of several feet is expected during a majorearthquake on the fault, which the pipeline is not designed for. In addition, the Agency’sSonoma aqueduct and the Oakmont pipelines cross the Bennett Valley fault and will likely fail ina surface rupturing event on this fault. Other vulnerable locations include the Russian Rivercrossing of the Russian River Cotati intertie and multiple stream crossings as shown in Figurexx. Depending upon the geometry of the stream bank and the potential for liquefaction, theselocations could have large lateral spread displacements and consequently the pipelines may fail.The Sonoma aqueduct is also vulnerable to damage from debris impact in a high flood scenarioat three locations where the pipeline is suspended from bridges across creeks.4.1.4 Storage FacilitiesThe Agency has a total of 17 flat bottom steel tanks located at eight independent sites. Out of the17 tanks, seven are anchored while the other 10 are unanchored. The tanks range in size from0.3 M.G. to 18 M.G. Most of the tanks have overconstrained piping connections that arepotentially vulnerable to damage in an earthquake. Such piping connections consist of the pipethat is rigidly attached to the tank shell and restrained by burial near the tank or connection to anadjacent nearby tank. As a result, the piping is unable to accommodate movement of the tank as32 Sonoma County Water Agnecy.doc

it tries to uplift due to seismic overturning moments. Most of the Agency’s tanks also havebottom penetrating inlet/outlet and drain piping. Typically, the steel tank base plate is relativelythin (typical thickness of ¼ inch) and is vulnerable to tearing if tank uplift occurs at the bottompenetration piping connection. The Agency is currently in the process of mitigating most ofthese vulnerabilities.4.1.5 Booster Pump FacilitiesThe Agency has eight booster stations. Five of the pump stations are single-story buildingswhile the other three are open to air. The most significant vulnerabilities include potentialdamage to the pump station building and electrical control cabinets. Minor to moderate damageto the pump station building may not necessarily be a significant hazard since the buildings arenot manned. However, major damage or collapse of the building can result in associated damageto the pump motor or motor control centers (MCC) by falling debris. A building that issignificantly damaged may also prevent or delay any required manual reset of pump controlsthereby impeding system operations. In terms of the potential for major collapse, the mostvulnerable pump stations are the Sonoma Booster Station because the pump stations are situatedwithin the fault deformation zone of the Bennett Valley fault.4.1.6 Treatment FacilitiesThe Russian River aquifer water is naturally filtered and does not require treatment. However, tomaintain regulatory levels of residual chlorine in the transmission system, the Agency has threechlorination facilities. Two of the three chlorination facilities are also corrosion control facilitiesto chemically treat the water’s pH to minimize the potential for corrosion. The three facilitiesinclude the Wohler chlorination and corrosion control facility located at the Agency’scorporation yard on Wohler Road, the Mirabel chlorination facility located near the Mirabelcollectors and the River Road chlorination and corrosion control facility located on River Road.The River Road facility is currently used only for corrosion control.The Mirabel and the Wohler facilities are single story reinforced masonry buildings thatgenerally perform adequately in an earthquake provided the buildings have adequate roof to wallconnections. The River Road facility is a two story masonry building with a soft first story andhas been retrofitted by the addition of braces at some of the open bays at the first floor.Typically buildings with soft first story perform poorly in earthquakes with excessive damage.The extent of potential damage to this building will depend upon the adequacy of the retrofitscheme. The most significant hazard at the treatment facilities is the potential for a chlorinerelease or damage to the contents and non-structural elements.33 Sonoma County Water Agnecy.doc

4.1.7 Supplementary Water SourcesIn addition to the main water source, the Russian River aquifer, the Agency has supplementarysources in three conventional wells located in the Santa Rosa Plain area. The three wells knownas the Occidental Road Well, the Sebastopol Road Well and the Todd Road Well collectivelyprovide a sustained flow of about 7 mgd. Two of the three wells are located in FEMA floodzone with the third located close to the boundary of the flood zone. Flooding at the site cansignificantly impact water quality and cause damage to the well infrastructure in terms of electricshort circuiting due to inundation and direct physical damage due to debris impact. All of thewells are located in medium to low liquefaction hazard areas. The most significant hazard froman earthquake viewpoint is the damage to the above ground infrastructure, communication andelectrical control systems from strong ground shaking.4.1.8 Emergency PowerThe Agency’s facilities receive power from PWRPA and PG&E including power to the Agencyowned substation at Wohler. This substation is a key component of the power network for theWohler and Mirabel collectors. Emergency power to all feeders in the substation is provided bythree 2000kW diesel generators, located near the Wohler Chlorination Building. The generatorsrequire manual start and can run for approximately 2.5 days before re-fuelling. Fuel for thegenerators is provided by a 25000 gal diesel tank located onsite. In addition, two 1250kW dieselgenerators are located near the Mirabel chlorination building. Fuel to these generators isprovided by 10,000 and 25000-gal fuel tanks located onsite. These generators can run forapproximately 5 days without re-fuelling. When all five generators are run at full power, nineout of ten pumps at the collectors (excluding new Collector #6) can be operated simultaneously.The chlorination facilities also have emergency generators for operating the chlorine sensors andscrubber systems. Emergency power to two of the eight booster stations is provided bygenerators located at the Sonoma Booster Station and the Ely Booster Station site. The Agencyalso has a series of uninterruptible power supply (UPS) units located at essentially all of theirfacilities to operate the communication and SCADA systems for a period of three to four hoursafter a major power loss.4.2 SANITATIONIndependent vulnerability assessment of Agency’s sanitation facilities has not yet beenperformed. Considering that these facilities are located in the same geographical region as thewater system facilities, they are also subject to the same types of hazards with similar types ofvulnerabilities. Figures 19 through 27 show the sanitation facilities overlain on maps of34 Sonoma County Water Agnecy.doc

significant hazards in Sonoma County. A general overview of the sanitation systemvulnerabilities is as follows:• Treatment facilities and lift stations within the Sea Ranch Sanitation Zone are located in closeproximity to the San Andreas Fault (Figure 19) and are subject to strong ground shakinghazard with PGA exceeding 0.5g (Figure 20).• The lift station for the Airport/Larkfield/Wikiup is located adjacent to the Rodgers Creek fault(Figure 19) and is subject to strong ground shaking hazard with PGA exceeding 0.6g (Figure20).• Sanitation facilities not in immediate proximity to the San Andreas or Rodgers Creek fault arestill located close enough to be subject to signification ground shaking with PGA exceeding0.4g.• Figure 21 shows the liquefaction and lateral spread hazard for the sanitation facilities.Facilities of the Geyserville Sanitation Zone, the treatment plant for the Russian RiverSanitation District and portions of the Sonoma Valley Sanitation District are located in high tovery high liquefaction zones. A significant number of the Agency’s sanitation facilities arelocated in medium liquefaction zones with some in zones of low liquefaction hazard.Pipelines, especially the pipeline connections to fixed facilities, are most vulnerable todamage within zones of potential liquefaction hazard.• Most of the Agency’s facilities are located outside the landslide hazard zone, with somefacilities, for example, lift stations of the Occidental County Sanitation Zone and theAirport/Larkfield/Wikiup Sanitation Zone and treatment plants for the Occidental CountySanitation Zone and the Russian River County Sanitation Zone are located in areas ofpotential landslide hazard (Figure 22).• Figure 23 shows that the potential for flooding hazard is high at the Geyservile SanitationZone, Russian River County Sanitation District, and the Forestville County SanitationDistrict.• Figure 24 shows that the debris flow hazard at the sanitation facilities is relatively low.• Figures 24 and 25 show that several facilities are located in areas that have corrosive soils,however, based on discussions with the Agency corrosion is not a predominant hazard.35 Sonoma County Water Agnecy.doc

• Facilities at the Sea Ranch Sanitation Zone, Occidental County Sanitation District, RussianRiver County Sanitation District and the Airport/Larkfield/Wikiup Sanitation Zone arelocated in areas of high fire hazard (Figure 26), with some of the facilities of the RussianRiver County Sanitation District and the Airport/Larkfield/Wikiup located close to theboundary of historic fire zones.• The Airport/Larkfield.Wikiup Sanitation Zone and the Sonomy Valley Sanitation Districthave wastewater treatment ponds with high embankments (California Division of Safety ofDams (DSOD), jurisdictional embankments) that could be subjected to high liquefaction andground shaking hazard and therefore, require detailed vulnerability assessment.A detailed multi-hazard reliability assessment of Agency’s sanitation facilities is a primary goalin this five year hazard mitigation plan. It is anticipated that mitigation of vulnerabilitiesidentified during this cycle of the plan will be included in the next five year cycle.4.3 FLOOD PROTECTIONIndependent vulnerability assessment of Agency’s flood protection facilities has not yet beenperformed. Considering that these facilities are located in the same geographical region as thewater system facilities, they are also subject to the same types of hazards with similar types ofvulnerabilities. A detailed multi-hazard reliability assessment of Agency’s flood protectionfacilities is a primary goal in this five year hazard mitigation plan. However, while the Agencyis responsible for the management of the large reservoirs (Lake Sonoma and Lake Mendocino),the primary responsibility of the reliability of major components of the infrastructure is with theU.S. Army Corps of Engineers. During this plan cycle the Agency will work with the Corps todevelop a plan to address the identified vulnerabilities in the future cycles of this plan. TheAgency is responsible for the reliability of reservoirs associated with the Central SonomaWatershed Project.4.4 ADMINISTRATIVE INFRASTRUCTUREIndependent vulnerability assessment of Agency’s administrative infrastructure has not yet beenperformed. A detailed vulnerability assessment of Agency’s office facilities is a primary goal inthis five year hazard mitigation plan. Upgrade of the identified vulnerabilities will be included inthe future cycles of this plan.36 Sonoma County Water Agnecy.doc

5.0 MITIGATION GOALS, OBJECTIVES AND ACTIONSSonoma County Water Agency is directly responsible for providing water to over 600,000people in the rapidly developing and expanding North Bay Area. The Agency is the primarywholesale provider of water to eight cities and water agencies who maintain their owndistribution networks but very little redundant sources of supply. The Agency’s contractors andin turn the public relies on the water supplied by the Agency for domestic water supply and forboth emergency and non-emergency, use such as irrigation and other domestic and industrialneeds.The Agency’s water system and its facilities stretch over an area of multiple natural hazards.The system has a range of vulnerabilities to these hazards. Hydraulic analysis conducted as partof the natural hazard vulnerability assessment of the water system show that damage to one ormore such facilities can deplete water storage and cause significant pressure loss at turnoutsserving the contractors within a matter of hours. Loss of supply from the Agency will leave thecontractors vulnerable in their ability to provide fire flow and drinking water to the public.The Agency takes this responsibility seriously and has developed this plan to systematicallyaddress the vulnerabilities of its water supply, wastewater collection and flood control systems.In this capacity, the Agency’s goals are in line with the goals of the community as addressed inthe Sonoma County (County) hazard mitigation plan. The County’s main goals are to reduce thevulnerability of people and property exposed to earthquake, landslide, flood, and wild-land firehazards. One of the objectives identified by the County for meeting these goals is to promote theimplementation of disaster mitigation projects identified as high priority through the SCWAmulti-hazard reliability assessment study and to increase the disaster resistance and reliability ofthe SCWA’s transmission system. Keeping in view the desires of the community, as expressedin the County’s plan and the understanding of the Agency vulnerabilities through a detailedmulti-hazard reliability assessment of its facilities, the Agency has formulated the followingthree main goals:Goal 1: Provide safe and reliable water supply to the public during and after a naturaldisaster to reduce the vulnerability of people and propertyGoal 2: Provide reliable wastewater collection, treatment and disposal services duringand after a natural disaster to reduce risk to the public’s health andenvironmental damageGoal 3: Maintain reliable flood control works to reduce the vulnerability of people andproperty to flood hazard37 Sonoma County Water Agnecy.doc

Based on the insights obtained from a comprehensive multi-hazard reliability assessment of theAgency’s water system, a series of mitigation goals and actions are included in this plan. Inaddition, first tier objectives and actions for the Agency’s wastewater collection and floodcontrol systems are also presented. The Agency believes that the upgrades and safe operations ofits systems require an ongoing program in which the most obvious vulnerabilities and those withthe highest probability of occurrence are mitigated first followed systematically byvulnerabilities with lower probabilities, or newly identified vulnerabilities based on newinformation, with a continued improvement in the reliability of the system. This process will bemanaged through continuous maintenance of this hazard mitigation plan through a five yearupdate cycle.Goal 1: Provide safe and reliable water supply to the public during and after a naturaldisaster to reduce the vulnerability of people and propertyObjective 1.1: Implement system-wide improvements that reduce the overall systemvulnerability by adding redundancy to the system and by enhancing Agency’s responsethrough better monitoring of its system.1.1.1 Minimize potential for uncontrolled release of water by providing isolation valves atstrategic locations.1.1.2 Plan, design and add redundant/emergency supply sources to minimize dependence onthe Russian River aquifer as the main source of water supply. Install new emergencyground water wells located strategically throughout the system.1.1.3 Provide seismic restraints to electrical and communication equipment at various facilities.1.1.4 Install flow measuring devices at key turnouts for real time monitoring of flow.1.1.5 Develop a GPS based system map with real-time monitoring at critical locations. Forexample, significant portions of the Agency’s aqueducts run through large zones ofundeveloped areas and pipe leaks in such areas are hard to precisely locate.1.1.6 Procure large diameter flexible hose and its deployment and retrieval system foremergency use.1.1.7 Install emergency manifolds at strategic locations to connect emergency hoses.Objective 1.2:Perform diversions system improvements1.2.1 Develop and implement designs to retrofit collectors against liquefaction and lateralspread hazard.1.2.2 Develop and implement design strategy to mitigate liquefaction and lateral spread hazardto the RDS.38 Sonoma County Water Agnecy.doc

Objective 1.3:Perform transmission system improvements1.3.1 Develop and implement a design strategy to mitigate fault rupture hazard to theaqueducts that cross the Rodgers Creek and the Bennett Valley faults.1.3.2 Develop and implement a design strategy to mitigate the liquefaction and lateral spreadhazard at the several river and creek crossings identified in the natural hazard reliabilityassessment. Some of the most vulnerable include the aqueduct crossings at RussianRiver, Petaluma River, Mark West Creek, Santa Rosa Creek and Calabasas Creek.1.3.3 Develop and implement a design strategy to mitigate the liquefaction, lateral spread andflood hazard for the Sonoma aqueduct suspended at the two pedestrian and one trafficbridge over Sonoma Creek at Lawndale Road, Madrone Road and Verano Avenue.1.3.4 Develop and implement a design or operational strategy to mitigate lateral spread damageto the Wohler-Mirabel Intertie.1.3.5 Develop plans to relocate or parallel the pipeline that crosses beneath the Spring Lakeand the Spring Lake dam.1.3.6 Develop a design or operational strategy to respond to unexpected pipeline damagewithin the Wohler-Mirabel area.1.3.7 Develop a long term strategy to address lower probability damage to transmission systempipelines. Due to the non-redundant nature of the transmission system such damage canbe just as disruptive as that due to damage with a high probability of occurrence.Objective 1.4:Perform pumping system improvements1.4.1 Develop and implement a retrofit design for mitigation of liquefaction and lateral spreadhazard at the Ely Booster station.1.4.2 Develop and implement a seismic retrofit design for the Kastania pump station building.1.4.3 Develop and implement a seismic retrofit design or replacement of the Wilfred boosterstation building.1.4.4 Develop and implement a design an operational solution, such as procuring large portablepumps, to mitigate the Bennett Valley fault rupture hazard to the Sonoma BoosterStation.Objective 1.5:Perform storage system improvements1.5.1 Perform a piping retrofit by replacing existing rigid piping with piping with flexiblejoints at the storage reservoirs.1.5.2 Implement other retrofits such as removing overconstrained conditions identified in thenatural hazard reliability study.39 Sonoma County Water Agnecy.doc

Objective 1.6:Improve the Agency’s emergency response capabilities1.6.1 Plan and procure stockpile material for use in emergency.1.6.2 Conduct first responder training of a broad pool of Agency’s personnel to respond in anemergency.1.6.3 Plan and develop a dedicated Emergency Operations Center such that the operators anddecision makers are in close proximity to each other.1.6.4 Procure a mobile EOC.Objective 1.7:Reliable emergency power systems1.7.1 Develop and implement design and operations plans to mitigate liquefaction relateddamage to electric power lines feeding collectors and pump stations.1.7.2 Procure and install additional UPS units at each facility to prolong the ability tocommunicate with the system beyond the current 4 hour limit.Objective 1.8:Reduce supply vulnerability1.8.1 Assess vulnerability of Russian River upstream of the aquifer to earthquake and nonearthquakeinduced landslides that could potentially block the river channel.1.8.2 Assess vulnerability of Russian River upstream of the aquifer to contamination fromaccidents and wildland fire.1.8.3 Design and implement mitigation schemes for reducing the potential of flood damage tothe well fields in the Mirabel and Laguna de Santa Rosa area.Objective 1.9:Minimize life safety risk and reduce operational vulnerability1.9.1 Conduct a detailed seismic vulnerability assessment of structural and non-structuralelements of the Agency’s facilities located at 404 Aviation Boulevard and CollegeAvenue.Objective 1.10:Improve understanding of fault rupture hazard1.10.1 Work with the United States Geological Survey (USGS) to design and conduct a detailedgeologic study including trenching of Bennett Valley and Rodgers Creek faults to moreaccurately define the fault activity and paleoseismic history of the fault, the rupture zoneand the extent of surface rupture.Objective 1.11:Minimize economic exposure to the Agency1.11.1 Work with the U.S. Army Corps of Engineers to expedite the earthquake safetyassessment of Warm Springs and Coyote Valley dams.40 Sonoma County Water Agnecy.doc

1.11.2 Conduct a detailed seismic vulnerability assessment of electric power station at the WarmSprings dam.1.11.3 Develop project design criteria document for new construction.Goal 2: Provide reliable wastewater collection, treatment and disposal services duringand after a natural disaster to reduce public health risk and environmentaldamageObjective 2.1: Improve the understanding of the vulnerability of the sanitation systemsunder the Agency’s control.2.1.1 Perform a multi-hazard vulnerability assessment of the sanitation systems.2.1.2 Develop project design criteria document for new construction.Goal 3: Maintain reliable flood control works to reduce the vulnerability of people andproperty to flood hazardObjective 3.1:protection works.Improve the understanding of the vulnerability of the Agency’s flood3.1.1 Perform a vulnerability assessment of the flood control works for multiple floodrecurrence intervals with consideration to potential impacts from global and local climatechange.3.1.2 Work with the U.S. Army Corps of Engineers to expedite reassessment of Coyote andWarm Springs dam under the revised PMF (probable maximum flood) conditions asimpacted by the recent PMP (probable maximum precipitation) study results included inthe hydro-meteorological report HMR57 for Pacific Northwest and HMR 58 and HMR59for California.3.1.3 Work with the U.S. Army Corps of Engineers to develop and implement a plan for theassessment of flood control levees within the Upper Russian River area betweenColverdale and Healdsburg.3.1.4 Develop project design criteria document for new construction.41 Sonoma County Water Agnecy.doc

6.0 IMPLEMENTATION STRATEGYFor the successful mitigation of hazards identified in this plan and to meet the Agency’s goalswithin a reasonable time frame, an implementation strategy has been developed. The strategyincludes an identification of the objectives identified in Section 6.0, development of planninglevel cost estimates and a time frame for implementation.The Agency’s implementation strategy includes first identifying a set of first tier objectives.These objectives are considered the highest priority and once implemented will result insubstantial improvement in the overall reliability of the system. The remaining objectives, notincluded in the first tier objectives, are considered desirable and will further enhance the systemreliability once the first tier objectives are achieved. In addition, the Agency, as part of itsmaintenance program, has undertaken some of the objectives identified in Section 5.0. The mostnoteworthy of these include; seismically restraining electrical and communication equipment(Objective 1.1.3), retrofitting overconstrained conditions at storage tanks (Objective 1.5.1 and1.5.2), procuring some stockpile material (Objective 1.6.1), working towards enhancing theemergency operations center (Objective 1.6.3) and reducing vulnerability of electric power lines(Objective 1.7.1).The Agency’s objectives have been prioritized based on the following:• Impact to the Agency’s system from the identified vulnerability. The system impacts werestudied through detailed hydraulic modeling of the system. Factors such as time to significantloss of pressure or significant loss of storage and the population impacted. For example, abreak at Rodgers Creek fault will result in loss of flow to the entire Sonoma Valley and isconsidered a high priority• Overall cost/benefit of the mitigation strategy. For example, anchorage of equipment at theAgency’s facilities is considered a high priority because of very high benefit to cost ratio.The Agency’s first tier objectives include:1. Mitigation Action 1.3.1 (partial) – Develop and implement design strategy tomitigate fault rupture hazard at Rodgers Creek fault crossing of Santa Rosaaqueduct2. Mitigation Action 1.1.4 – Install flow measuring devices at key turnouts for realtime monitoring of flow42 Sonoma County Water Agnecy.doc

3. Mitigation Action 1.1.1 – Minimize potential for uncontrolled release of waterby providing isolation valves at strategic locations4. Mitigation Action 1.3.2 (partial) – Develop and implement design strategy tomitigate the liquefaction and lateral spread hazard at the Russian River crossing5. Mitigation Action 1.3.2 (partial) – Develop and implement design strategy tomitigate the liquefaction and lateral spread hazard at the Mark West Creekcrossing6. Mitigation Action 1.2.1 (partial) – Develop and implement retrofit design forCollectors 3 and 5 against liquefaction and lateral spread hazard7. Mitigation Action 1.2.1 (partial) – Develop and implement retrofit design forCollector 6 against liquefaction and lateral spread hazard8. Mitigation Action 1.1.2 – Plan, design and add redundant/emergency supplysources to minimize dependence on the Russian River aquifer as the main sourceof water supply. Install new emergency ground water wells located strategicallythroughout the system (assumed three locations)9. Mitigation Action 1.3.2 (partial) – Develop and implement design strategy tomitigate the liquefaction and lateral spread hazard at the Santa Rosa Creekcrossing10. Mitigation Action 1.2.2 – Develop and implement design strategy to mitigateliquefaction and lateral spread hazard to the RDSThe implementation strategy has been developed based on the recommended CapitalImprovement Program developed as part of the multi-hazard reliability project. Once theseobjectives are achieved, implementation schedule and planning level budget estimates for secondtier objectives can be developed in future revisions to the plan, if so desired by the Agency, thepublic and the Agency’s contractors. The first tier mitigation actions are included in theAgency’s Capital Improvement Program (CIP), which is administered by the Engineering andResource Planning Division with the other division heads involved in the yearly CIPdevelopment cycle.The Agency will actively work towards identifying funding sources for these projects. Some ofthese sources include: FEMA’s pre-disaster mitigation program (PDM) and hazard mitigation43 Sonoma County Water Agnecy.doc

grants program (HMGP), Agency’s maintenance budget and a proposed reliability surchargewithin the Agency’s rate structure. Since 2003, FEMA has provided close to $540 million inPDM grants to eligible projects. Additional funding from FEMA is available following aFederal disaster declaration as part of its HMGP.Depending on the level of funding available, the Agency plans to implement the top six first tierobjectives in 4 to 10 years following the adoption of this plan with the remainder of the first tierobjectives completed within the next 15 to 25 years.44 Sonoma County Water Agnecy.doc

7.0 PLAN MAINTENANCEThe Agency’s commitment to reducing its hazard vulnerability and improving the reliability ofits system is demonstrated by the fact that the Agency on its own initiative undertook acomprehensive multi-hazard reliability improvement program. The Agency recognizes that thiscommitment can only be met through a dedicated effort. Development of the Hazard MitigationPlan is part of this effort. In meeting the requirements of the DMA2000, the Agency plans toupdate the Hazard Mitigation Plan every five years or if new information becomes available,priorities for implementation change or an actual hazard event occurs that may prompt an updateto the plan sooner than five years.7.1 MONITORING EVALUATING AND UPDATING THE PLANThe Agency will keep the plan “alive” through constant monitoring of the plan goals andobjectives. The high priority mitigation actions are being included in the Agency’s CIP.Because of the involvement of the Agency’s Department heads of Planning, Operations,Maintenance and Capital Improvements in the development of the plan, the entire executivemanagement of the Agency is committed to implement the goals and objectives of the plan.The Agency will incorporate the hazard mitigation plan in its yearly CIP planning process tomonitor progress towards the goals of the hazard mitigation plan. To further facilitate thisprocess, the Agency’s Capital Projects Manager has been identified as the person responsible formonitoring and updating the hazard mitigation plan. As required by DMA2000, this plan will beupdated every five years. The Agency will also update the plan if there is a significant change inthe basic assumptions, for example a major hazard event that highlights vulnerabilities in thesystem not anticipated at the present time.7.2 CONTINUED PUBLIC INVOLVEMENTThe Agency, with its decision to incorporate the hazard mitigation plan in its yearly CIPplanning process, has ensured continued public involvement in this plan. The CIP approval is anopen public process. As part of the approval process the CIP is presented to the Agency’s Boardof Supervisors in an open public meeting and by virtue of this, progress towards achievingAgency’s goals and objectives identified in the hazard mitigation plan will also be open forpublic review and comment.Further, the Agency is contractually obligated to meet on a regular basis with two advisorycommittees. The Water Advisory Committee (WAC) and the Technical AdvisoryCommittee(TAC) meet quarterly and monthly respectively. The WAC is made up of members45 Sonoma County Water Agnecy.doc

of the elected Councils and Boards of the Agency’s contractors and they discuss the Agency’sprograms and budget in an open public forum. They are responsible for makingrecommendations on the Agency’s budget to the Agency’s Board of Directors. The TACconsists of managers and technical staff of the Agency’s contractors. They meet to discuss theday to day operation of the Agency’s system and to discuss the need for capital and mitigationprojects. The Plan will be a regular topic of discussion before both of these groups.46 Sonoma County Water Agnecy.doc

eferences1 Sonoma County Water Agency, Draft Report – Phase I for Natural Hazard ReliabilityAssessment of Water Supply and Transmission System, 2/10/2005, prepared by MMIEngineering.2 Sonoma County Water Agency, Draft Report – Seismic Assessment of Water StorageTanks and Rodgers Creek Fault Deformation Zone, 4/15/2005, prepared by MMIEngineering.3 Sonoma County Water Agency, Draft Technical Memorandum – Seismic VulnerabilityAssessment of Diversion System Caissons, 12/14/2006, prepared by MMI Engineering.4 Sonoma County Water Agency, Addendum I, Draft Technical Memorandum – SeismicVulnerability Assessment of Transmission System, 02/6/2007, prepared by MMIEngineering.5 Sonoma County Water Agency, Draft Technical Memorandum – Seismic VulnerabilityOverview of Contractor Systems, 03/29/2007, prepared by MMI Engineering.6 Sonoma County Water Agency, Technical Memorandum – Power Supply of SCWAFacilities, 06/05s/2006, prepared by MMI Engineering.7 Sonoma County Transmission System Reliability Study, Final Emergency Well SiteSelection Results, 7/23/2007, prepared by HydroMetrics LLC.8 Sonoma County Water Agency, Emergency Operations Plan, Revision No. 6, September,1998, Operations Edition.9 Sonoma County Water Agency, Emergency Operations Plan, Revision No. 6, September,1998, Management Edition.10 Sonoma County Water Agency; 2005 Urban Water Management Plan, December 2006.11 FEMA, 386-1 State and Local Mitigation Planning, How-To Guide, Getting StartedBuilding Support for Mitigation Planning, September 2002.12 FEMA, 386-2 State and Local Mitigation Planning, How-To Guide, Understanding YourRisks, Identifying Hazards and Estimating Losses, August 2001.13 FEMA, 386-2 State and Local Mitigation Planning, How-To Guide, Understanding YourRisks, Identifying Hazards and Estimating Losses, August 2001.14 FEMA, 386-3 State and Local Mitigation Planning, How-To Guide, Developing theMitigation Plan, Identifying Mitigation Actions and Implementation Strategies, April2003.15 FEMA, 386-4 State and Local Mitigation Planning, How-To Guide, Bringing the Plan toLife, Implementing the Hazard Mitigation Plan, August 2003.16 FEMA, 386-5 State and Local Mitigation Planning, How-To Guide, Using Benefit-CostReview in Mitigation Planning, May 2007.17 Sonoma County Hazard Mitigation Plan, Sonoma County Department of EmergencyServices & Sonoma County Permit and Resource Management Department, AdoptedSeptember 19, 2006.47 Sonoma County Water Agnecy.doc

18 Local Hazard Mitigation Planning Guidance, provided by Tennessee EmergencyManagement Agency19 Orange County Regional Water and Wastewater Multi-Hazard Mitigation Plan, OrangeCounty, California, Municipal Water District of Orange County, Final Draft Report,September 29, 2006.20 Meeting June 2, 2005, Alder Conference Room, 404 Aviation Boulevard, Santa Rosa:Attendees: Jay Jasperse (Deputy Chief Engineer, Engineering and Resource Planning),Cordel Stillman (Capital Projects Manager) Sonoma County Water Agency, AhmedNisar, MMI Engineering, George Roberts, Forestville Water District and Richard Burt(for Matt Mullan), Town of Windsor.21 Meeting June 2, 2005, Sequoia Conference Room, 404 Aviation Boulevard, Santa Rosa:Attendees: Jay Jasperse (Deputy Chief Engineer, Engineering and Resource Planning),Cordel Stillman (Capital Projects Manager) Sonoma County Water Agency, AhmedNisar, MMI Engineering, Darin Jenkins, City of Rohnert Park and Mike Ban, City ofPetaluma.22 Meeting June 7, 2005, Alder Conference Room, 404 Aviation Boulevard, Santa Rosa:Attendees: Jay Jasperse (Deputy Chief Engineer, Engineering and Resource Planning),Cordel Stillman (Capital Projects Manager) Sonoma County Water Agency, AhmedNisar, MMI Engineering, Krishna Kumar, Valley of the Moon Water District and AlBandur, City of Sonoma.23 Meeting August 26, 2005, 404 Aviation Boulevard, Santa Rosa: Attendees: Jay Jasperse(Deputy Chief Engineer, Engineering and Resource Planning), Cordel Stillman (CapitalProjects Manager) Sonoma County Water Agency, Ahmed Nisar, MMI Engineering,Chris DeGabriele, North Marin Water District.24 Meeting September 15, 2005, 404 Aviation Boulevard, Santa Rosa: Attendees: JayJasperse (Deputy Chief Engineer, Engineering and Resource Planning), Cordel Stillman(Capital Projects Manager) Sonoma County Water Agency, Ahmed Nisar, MMIEngineering, Miles Ferris, City of Santa Rosa.25 Earthquake probabilities in the San Francisco Bay region: 2002-2031, a summary offindings: United States Geological Survey Open File Report 03-214.http://geopubs.wr.usgs.gov/open-file/of03-214, prepared by WGCEP (Working Group onCalifornia Earthquake Probabilities), 2003.26 Suppression of large earthquakes by stress shadows: a comparison of Coulomb and rateand-statefailure: Journal of Geophysical Research, v. 103, p. 24,439, by Harris, R.A.,and Simpson, R.W., 1998.27 The Santa Rosa Earthquakes of October, 1969, in Mineral Information Service:California Division of Mines and Geology, v. 23, no. 3, p. 43-63, by Cloud, W.K., Hill,D.M., Huffman, M.E., Jennings, T.V., McEvily, T.V., Nason, R.D., Steinbrugge, K.V.,Tocher, D., Unger, J.D., Youd, T.L., 1970.28 Contemporary seismicity, active faulting and seismic hazards of the Coast Rangesbetween San Francisco Bay and Healdsburg, California: Journal of GeophysicalResearch, v. 96, no. B12, p.19,891-19,904 by Wong, I.G., 1991.48 Sonoma County Water Agnecy.doc

29 "Mare Island" earthquake at the southern end of the Rodgers Creek fault, in Borchardt,G., and others, eds., Proceedings of the Second Conference on Earthquake Hazards in theEastern San Francisco Bay Area: California Division of Mines and Geology SpecialPublication 113, p. 385-392, by Toppozada, T.R., Bennett, J.H., Hallstrom, C.L., andYoungs, L.G., 1992, 1898.30 The Santa Rosa, California Earthquake of October 1, 1969 prepared by K.V. Steinbrugge,W.K. Cloud and N.H. Scott for U.S. Department of Commerce, Environmental ScienceServices Administration, 1970.31 Slip rate, earthquake recurrence, and seismogenic potential of the Rodgers Creek faultzone, northern California: Initial Results: Geophysical Research Letters, v. 18, no. 3, p.447-450, by Budding, K.E., Schwartz, D.P., and Oppenheimer, D.H., 1991.32 Late Holocene behavior and seismogenic potential of the Rodgers Creek fault zone,Sonoma County, California, in Borchardt, G., et al., eds., Proceedings of the SecondConference on Earthquake Hazards in the Eastern San Francisco Bay Area: CaliforniaDivision of Mines and Geology Special Publication 113, p. 393-398, by Schwartz, D.P.,Pantosti, D., Hecker, S., Okumura, K., Budding, K.E., and Powers, T., 1992.33 The Bay Area Earthquake Cycle: A paleoseismic perspective: Eos (AmericanGeophysical Union, Transactions), v. 82 (47), p. Abstract S12F-07 by Schwartz, D.P.,Seitz, G., Lienkaemper, J., Dawson, T., Hecker, S., Lettis, W., and Kelson, K., 2001.34 Toppozada T. et al., 1994, Planning Scenario for a Major Earthquake on the RodgersCreek Fault in the Northern San Francisco Bay Area, CDMG Special Publication 112.35 McLaughlin, R.J., and Sarna-Wojcicki, A.M., 2003, Geology of the right stepover regionbetween the Rodgers Creek, Healdsburg, and Maacama faults, northern San FranciscoBay region: U.S. Geological Survey Open-File Report 03-502, 23 p.,http://geopubs.wr.usgs.gov/open-file/of03-502.36 Empirical Response Spectral Attenuation Relations for Shallow Crustal Earthquakes,Seismological Research Letters, Vol. 68, No. 1, prepared by N.A. Abrahamson and W.J.Silva, January/February 1997.37 "Empirical Analysis of Horizontal Ground Displacement Generated by Liquefaction-Induced Lateral Spread” Technical Report NCEER-92-0021 by Bartlett, S. F. and Youd,T. L.1992 for National Center for Earthquake Engineering Research (NCEER).38 "Revised Multilinear Regression Equations for Prediction of Lateral SpreadDisplacements" Journal of Geotechnical Engineering, ASCE, by Bartlett, S. F. and Youd,T. L., 2002.39 ‘‘Historic ground failures in northern California triggered by earthquakes.’’ ProfessionalPaper 993, U.S. Geological Survey, Menlo Park, Calif., 177, by Youd, T. L., and Hoose,S. N. 1978 .40 State of California; The Resources Agency; Department of Water Resources; Preparingfor California’s Next Drought, Changes Since 1987-92, July 2000.41 State of California; Department of Water Resources; Drought Preparedness,http://watersupplyconditions.water.ca.gov.42 The Weather Channel http://www.weather.com/encyclopedia/tornado/climo.html.49 Sonoma County Water Agnecy.doc

43 The Tornado Project http://www.tornadoproject.com.44 Source: The Weather Channelhttp://www.weather.com/encyclopedia/tropical/climo.html.45 Source: The USA TODAY Weather Book by Jack Williams). (Source: USA Todaywebsite http://www.usatoday.com/weather/whpacg.htm.46 Preliminary Reports from the Hyogo-ken Nambu Earthquake of January 17, 1995,prepared by the Multidisciplinary Center for Earthquake Engineering Research(MCEER).47 Using GIS to Assess Water Supply Damage from the Northridge Earthquake, prepared byThomas O’Rourke and Selcuk Toprak for the National Center for EarthquakeEngineering Research (NCEER) Bulletin.50 Sonoma County Water Agnecy.doc

APPENDIX ATable A-1List of Drawings ReviewedS. No Name of the File Year1. Russian River Cotati Intertie Project – Pipe Contract No. 1 Contract No 60-4-7#1 19752. Russian River Cotati Intertie Project – Pipe Contract No. 2 Contract No 60-4-7#2 19753. Russian River Cotati Intertie Project – Pipe Contract No. 3 Contract No 60-4-7# 19754.Special Provisions And Contract Drawings For Construction of Russian River Project – SonomaAqueduct Pipeline and Appurtenances19625.Special Provisions And Contract Drawings For Construction of Russian River Project – SonomaAqueduct Glen Ellen Branch19646. Russian River Project – Aqueduct Number 1 19577. Petaluma Aqueduct Water Transmission Pipeline 19638. Oakmont Pipeline Contract No 60-4-7#5 19889. Eldridge Madarone Pipeline Project 200510.Kawana Springs Pipeline East (Petaluma Aqueduct To Kawana Springs Tank No.1) Contract No. 60-4-7200111.Pump and Collector Capacity Project – Caisson and Access Road For Wohler Collector No. 6 ContractNo. 60-5-7200112. Pump and Collector Capacity Project Wohler-Forestville Pipeline 2004A-1 Sonoma County Water Agnecy.doc

S. No Name of the File Year13.Special Provisions And Contract Drawings For Construction of Russian River Project – HorizontalWater Collectors Near Mirabel at The Russian River 60-5-7#1197314.Special Provisions And Contract Drawings For Construction of Mirabel Collector No. 5 Contract No60-5-7#5198215.Project Manual Volume 2 For Pump and Collector Capacity Project – Wohler Forestville PipelineContract No 60-4-7#10200416.Russian River Well Field Development (Equipment) Early Warning System Station No. 1 And MirabelInflatable Dam Fabric Replacement199517.Specifications and Contract Drawings For Wohler Site Improvements: Standby GeneratorReplacement and Temporary Power Delivery System (PDS) For Substation Replacement Contract No60-6-7#27200018.Sonoma County Water Agency: Wohler/Mirabel 12 KV Underground and Overhead Power LineModifications200619.Project Manual Volume 2 For Pump and Collector Capacity Project Pumphouse and ConnectingPipeline For Wohler Collector #6 Contract No 60-4&6-7#1200220. Project Manual For Eldridge-Madrone Project Contract No 60-4-7#11 200421.Kawana Springs Pipeline West (Vicinity of Wright Road To Petaluma Aqueduct) And Russian RiverWell Field Valve Replacements (Mirabel Area) Contract No 60-4-7#8 & 60-6-7#19199922 Special Provisions and Contract Drawings for Ralphine Reservoir No. 3 Contract No 60-7-7 No.2 197023Special Provisions and Contract Drawings for Grading and Appurtenances For Ralphine Reservoir No.3 Contract No 60-7-7 No. 1197024Project Manual And Contract Drawings For Construction OF Anadel reservoir No.2 And CotatiReservoir No.3 Contract No 60-7-7 No.23199225Project Manual And Contract Drawings For Grading Piping and Appurtenances For Anadel reservoirNo.2 , Cotati Reservoir No.3 and Warm Springs Reservoir Contract No 60-7-7 No.21198526Special Provisions and Contract Drawings for Construction of Russian River Cotati Intertie Project:Grading and Appurtenances Cotati Reservoir Contract No 60-7-7 No.71974A-2 Sonoma County Water Agnecy.doc

S. No Name of the File Year27Special Provisions and Contract Drawings for Construction of Russian River Cotati Intertie Project:Cotati Reservoir Contract No 60-7-7 No.8197428Special Provisions and Contract Drawings: Grading and Appurtenances for Ralphine Reservoir No. 4Contract No 60-7-7 No.5197329Special Provisions and Contract Drawings for Construction of Russian River Cotati Intertie Project:Ralphine Reservoir No. 4 Contract No 60-7-7 No.6197430Specifications and Contract Drawings For Ralphine Tank No.4 Valve Seismic Control System ContractNo 60-7-7 No.51199931Special Provisions and Contract Drawings Russian River Project For Construction Of RalphineReservoir No.2 For Petaluma Aqueduct196132Special Provisions and Contract Drawings for Construction of Russian River Cotati Intertie Project:Grading and Appurtenances Cotati Reservoir No. 2 Contract No 60-7-7 No.10198033Special Provisions and Contract Drawings for Construction of Russian River Cotati Intertie CotatiReservoir No. 2 Contract No 60-7-7 No.11198034 Specifications and Contract Drawings For Kawana Springs Tank No.1 Contract No 60-7-7 No.45 199835Special Provisions and Contract Drawings For Construction Kastania Reservoir Contract No 60-7-7No.14198336Specification and Contract Drawings For Seismic Retrofit For Eldridge Reservoir No.1 & ForestvilleReservoirs No. 1 & No.2199537Special Provisions And Contract Drawings Grading and Appurtenances For Eldridge Reservoir No. 2Contract No: 60-7-7 #3197238Specification and Contract Drawings For Seismic Retrofit For Anadel Reservoir No.1 & SonomaReservoir No. 1 Contract No. 60-7-7 #29199439Specification and Contract Drawings For Seismic Retrofit for Eldridge Reservoir No.1 & ForestvilleReservoir No.1 & No.2 Contract No. 60-7-7 #37199540Special Provisions And Contract Drawings For Construction of Grading, Piping and AppurtenancesFor Forestville Reservoir No. 2 Contract No: 60-7-7 #161989A-3 Sonoma County Water Agnecy.doc

S. No Name of the File Year41Special Provisions And Contract Drawings For Construction of Forestville Reservoir No. 2 ContractNo: 60-7-7 #17199042Special Provisions And Contract Drawings: Russian River Project For Construction of ForestvilleReservoir No. 1196143Special Provisions And Contract Drawings For Construction of Sonoma Reservoir No. 2 GradingPiping and Appurtenances Contract No: 60-7-7 #15199144Special Provisions And Contract Drawings: Russian River Project For Construction of StorageReservoirs For Sonoma Aqueduct Contract No. 52-7-7#21962A-4 Sonoma County Water Agnecy.doc

Table A-2List of Facility Geotechnical Reports ReviewedS. No Title Consultant Date12Geotechnical Investigation Proposed SeismicRepair Work Mirabel Collectors NOS. 3 AND 4Sonoma County, California For The SonomaCounty Water Agency.A Geophysical Survey of the Wohler Aquifer StudyArea Russian River, CaliforniaConsulting Engineers 08-13-1985NORCAL Geophysical Consultants 09-14-19873Hydrogeologic Investigation Wohler Aquifer StudySonoma County, CaliforniaHarding Lawson Associates 12-09-198845Report of Findings Preliminary Soil andGroundwater investigation: Wohler Road PumpingFacilityReport of Hydrogeologic Evaluation Russian Riverwell Field Investigation (Near Mirabel) SonomaCounty, CaliforniaBrunsing Asociates Inc 09-30-1991Herzog Associates, Inc 12-16-19926Seismic Refraction Survey Russian River Well FieldInvestigation Sonoma County, California.Harding Lawson Associates 04-30-19937Hydrogeologic Evaluation Kaiser sand and gravelcompany property Healdsburg, California.PES Environmental, Inc 12-17-19988Hydrogeologic Evaluations Westside Farms andLazy "W" Ranch Healdsburg, CaliforniaPES Environmental, Inc 12-11-19989Seismic Refraction Survey Pump and CollectorCapacity Project Sonoma County, CaliforniaNORCAL Geophysical Consultants 06-07-19991011Geotechnical Investigation Sonoma County WaterAgency pH Adjustment/Corrosion Control Facility9750 Wohler Road, Sonoma County, CaliforniaGeotechnical Investigation Sonoma County WaterAgency Wohler Substation Replacement 9750Wohler Road, Sonoma County, CaliforniaBrunsing Associates 02-28-1994Brunsing Associates 02-15-199912Geotechnical Investigation Wohler Collector 6Pumphouse Sonoma County, CaliforniaRGH Geotechnical andEnvironmental Consultants04-26-200213 Seismic Refraction Survey Wohler PipelineRGH Geotechnical andEnvironmental Consultants04-200114Geotechnical Investigation Proposed SeismicRetrofit Annadel Reservoir No. 1 Sonoma County,CaliforniaBrunsing Associates 06-25-199515Geotechnical Investigation Collector 6 Pipeline AndWohler-Forestville Pipeline Projects SonomaCounty, California.RGH geotechnical andEnvironmental Consultants06-25-1995A-5 Sonoma County Water Agnecy.doc

S. No Title Consultant Date1617Geotechnical Investigation Report For SeismicRetrofits of Eldridge Reservoir No.1 ANDForestville Reservoir NOS. 1 & 2 Sonoma CountyCaliforniaStructural Evaluation of the Sonoma County WaterAgency Administration Building and O&M Centerfor Seismic Conditions.Kleinfelder, Inc 03-03-1995MKM & Associates 06-03-199718 Summary of Subsurface Investigations WLA 04-21-200619Geological Investigation For The Proposed SantaRosa Creek Dam and ReservoirWoodward, Clyde, Sherard andAssociates02-24-5920Geology of the Healdsburg Quadrangle, CaliforniaMineralogy of the California Glaucophone Schists,State of Califonia (Including Maps)July 195121 Geotechnical Assessment of Aqueduct System WLAOctober2006A-6 Sonoma County Water Agnecy.doc

475 14 th StreetSuite 400Oakland, CA 94612Tel: 510 836 3002Fax: 510 836 3036APPENDIX BBoard of SupervisorsResolution for Adoption ofSonoma County Water Agency Local Hazard Mitigation PlanSonoma County Water Agnecy.doc

RUSSIAN RLegendSCWA FacilitiesFacility type= Booster Station!( Chlorination FacilityED Collector Stationd¾ Corrosion Control FacilityDiversion Structure^Thurston Creekkj Storage TankTannery CreekMirabel Well FieldAgua Caliente CreekV Production WellsOther FaultsArroyo SecoGossage CreekQuaternary & Pre-Quaternary FaultsBennett Valley FaultFault TraceRodgers Creek FaultConcealedInferredApproximateSche l SloughWell Located* Pipeline route are approximatedfrom drawingsµFigure 1Humbug CreekMill CreekMirabel Wells 1-7Mirabel ChlorinationMirabel Collectors(No. 1 - 3)!(River Road Chlorine andCorrosion ControlEDEDEDWohler Collectors#1, #2 & #6^EDEDd¾!(d¾!(= kjkjForestville Tanks(0.3 and 1 MG)ForestvilleBooster StationSEE INSETPool CreekHobson CreekMARK WEST CRWohler Chlorination andCorrosion ControlVan Buren CreekMARK WEST CROccidentalRoad WellVV_WindsorWeeks CreekRincon CreekV_Kawana SpringsBooster Station=SebastopolRoad WellLarkfieldDucker CreekTodd RoadWell§¨¦ 101_kjSonoma BoosterStation(No. 1 and 2)Smith CreekKawana SpringsTank(10 MG)kjkjkjkj=Piner CreekDuvoul CreekSanta RosaRalphineTanks( 6, 6, 6and 18 MG)kjAnnadel Tank 2(3 MG)SANTA ROSA CRkjMATANZAS CRGREEN VALLEY CRGrab CreekDutch Bi l CreekAnnadel Tank 1(2.5 MG)Lancel CreekAtascadero CreekPurrington CreekCalabazas Creek§¨¦ 12Yulupa CreekStuart Creek=Wilfred BoosterStation1 Wohler Chlorine &§¨¦ 1 Wohler Collector #1Corrosion ControlCotatikjkjkj _Cotati Tanks(6, 12 and 18 MG)Wohler Collector #2Pengrovekjkj__River DiversionEly Booster= StationPetalumaMirabel Wells_§¨¦ 116Kastania Tankkj = Kastania (12 MG)StationBooster§¨¦ 121_Copeland CreekEldridgeBoosterStation= kjkjEldridge Tanks(2 and 6 MG)Nolan CreekPorter CreekCrane CreekRohnert ParkSALMON CRMill CreekEbabias CreekLichau CreekSONOMA CRAmericano CreekSonoma Tanks(2 and 8 MG)Dowdall CreekSonomaWillow BrookNathanson CreekCarriger CreekMirabel ChlorinationFelder CreekLewis CreekRodgers CreekPETALUMA RSTEMPLE CRFowler CreekChamplin CreekLynch CreekADOBE CRMirabel Collectors(No. 1-3)Wohler Chlorine #6RUSSIAN RRUSSIAN RRUSSIAN RMARK WEST CRTOLAY CRDonahue SloughSchultz SloughWater System MapFay CreekRUSSIAN RRUSSIAN RFife CreekRUSSIAN RRUSSIAN R

Blue Jay Creek!(Coleman Valley CreekHot Springs CreekPorterfield CreekGalloway Creek!(!( !( !( !(!(!(Sea RanchSanitation ZoneGeyservilleSanitation ZoneDRY CR!(!(System MapWhite CreekCrocker CreekOsser CreekBIG SULPHUR CRIcaria CreekLITTLE SULPHUR CRBrush CreekGill CreekFlat Ridge CreekBUCKEYE CRBarrelli CreekSoda Springs CreekSAUSAL CRHouse Creektu 128tu 1 §¨¦ 101Russian River CountySanitation DistrictAirport / Larkfield / WikiupSanitation Zone!(!(!(!(!(!( !( tu 116 !(!( Forestville County!(Sanitation District!(!( Graton SanitationZone!(!(!(!( Occidental CountySanitation Districttu 12!(South Park CountySanitation District!(!(!(Copeland CreekSonoma ValleySanitation District!(Pengrove SanitationZonetu 116tu 121LegendDutcher CreekGrasshopper Creek!(!(Lift StationBurns CreekMiller CreekBear CreekRancheria CreekWaste Water Treatment PlantTombs CreekMill StreamStrawberry CreekSanitation District/Zone BoundaryMcDonnell CreekBluegum CreekFall CreekBriggs CreekCoon CreekGird CreekPena CreekWillow Springs CreekFuller CreekBritain CreekYellowjacket CreekMAACAMA CRWine CreekChapman BranchRedwood Log CreekWARM SPRINGSFall CreekPena CreekDanfield CreekKelley CreekPechaco CreekCedar CreekRedwood CreekBidwell CreekFRANZ CRWallace CreekWoods CreekSulphur CreekAngel CreekDevil CreekBrooks CreekGray CreekRed Slide CreekMcKenzie CreekMarshall CreekMILL CRBarnes CreekFelta CreekBearpen CreekMiller CreekGilliam CreekThompson CreekWarren CreekPorter CreekWindsor CreekRUSSIAN RCarson CrPress CreekOsborne CreekSchoolhouse CreekBlack Rock CreekWard CreekHumbug CreekPool CreekFife Creek# Hulbert CreekMill CreekTurner CanyonTimber Cove CreekMARK WEST CRHobson CreekVan Buren CreekRUSSIAN RMission CreekWeeks CreekSANTA ROSA CRDucker CreekRincon CreekPiner CreekSmith CreekRUSSIAN RAUSTIN CROrrs CreekSheephouse CreekRussian GulchBohemian CreekRUSSIAN RRUSSIAN RMATANZAS CRPurrington CreekDutch Bill CreekWillow CreekAtascadero CreekFurlong GulchCalabazas CreekRough CreekFay CreekFinley CreekStuart CreekSONOMA CRYulupa CreekScotty CreekNolan CreekThurston CreekTannery CreekCrane CreekSALMON CREbabias CreekCarriger CreekGossage CreekCheney GulchQuinlan GulchJohnson GulchPACIFIC OCEANArroyo SecoWillow BrookLichau CreekAmericano CreekPACIFIC OCEANRodgers CreekSTEMPLE CRFelder CreekLynch CreekChamplin CreekPETALUMA R!(ADOBE CRSchultz SloughTOLAY CRPorter CreekFranchini CreekStewarts CreekLittle CreekGUALALA R, S FKROCKPILE CR³0 1 2 3 Miles*Sanitation Districts/Zones are encircled for emphasisSanitation District and Zones MapFigure 2

21Wohler and MirabelProduction Facilities201918RDS117RDS2WF1WF1WF21615141312111098765432Wohler and MirabelProduction Facilities31EP15EP1430EP11EP12EP10EP9EP8EP7EP6EP5EP4EP3EP2 EP129EP13282726252423T2-2T2-4 T2-3 T2-5T2-122Power SystemFigure 3

tu 101 §¨¦ 280 §¨¦ 880Coyote Valley Dam!(§¨¦ 5HEALDSBURG FAULTWarm Springs Dam!(MAACAMA FAULT§¨¦ 505tu 101 tu 101Sonoma CountyAustin Creek State Rec AreaSanta Rosa SCWA Water System§¨¦ 80NapaPetalumaFairfieldVallejo§¨¦ 780Point Reyes Natl SeashoreNovatoGolden Gate National Rec Area§¨¦ 580 ConcordMount Tamalpais State Parktu 101tu 101 San FranciscoOakland§¨¦ 280SAN ANDREAS FAULTtu 101 tu 1RODGERS CREEK FAULT§¨¦ 380 §¨¦ 980CONCORD GREEN VALLEY FAULTHAYWARD FAULTAntiochMount Diablo StateLivermorµMiles0 10 20San JoseFault Map of the Bay Area Figure 4

CONFIDENTIALSource: USGS – http://quake.wr.usgs.gov/research/seismology/wg02/media.htmlHistoric Earthquakes in the Bay AreaFigure 5

CONFIDENTIALSource: USGS – http://quake.wr.usgs.gov/research/seismology/wg02/media.htmlEarthquake Probabilities in the Bay Area Figure 6

Fault Map of Agency’s Service Area Figure 7

Press CreekDowdall CreekLivereau CreekFife CreekRUSSIAN RRUSSIAN RWohler IntertieRussian River Well FieldMirabel ChlorinationInflatable Damand RDSRiver Road Chlorine andCorrosion ControlFay CreekDutch Bill CreekRUSSIAN RSmith CreekDuvoul CreekGrab CreekLancel CreekSALMON CRPorter CreekMirabelCollectors(No. 3, 4 and 5)GREEN VALLEY CRPurrington CreekWohler Collectors(No.1 and 2)ForestvilleBoosterStationRUSSIAN RCotati 1ForestvilleAqueductForestville Tanks(0.3 and 1 MG)Atascadero CreekOccidentalRoadWellWindsor CreekPool CreekWohler Chlorination andCorrosion ControlSANTA ROSA CRKawana 1Kawana SpringsBooster StationSebastopolRoadWellSanta Rosa 1Kawana 2Todd RoadWellPiner CreekSanta Rosa 2Santa Rosa 3MATANZAS CRMill CreekRincon CreekPetaluma 1Kawana 3Petaluma 2Ducker CreekHumbug CreekSonoma BoosterStation(No. 1 and 2)Sonoma 1Kawana SpringsTank(10 MG)RalphineTanks(6, 6, 6and 18 MG)Weeks CreekMARK WEST CRVan Buren CreekPorter CreekAnnadel Tank 1(2.5 MG)OakmontAnnadel Tank 2(3 MG)Yulupa CreekSonoma 2Calabazas CreekLiquefaction andLateral Spread HazardLegendSCWA FacilitiesFacility typeBooster StationChlorination FacilityCollector StationCorrosion Control FacilityDiversion StructureHydroWater MeterStorage TankRussian River Well FieldProduction WellsAqueductAqueduct Node PointsCreek crossingsLiquefaction PotentialVery LowLowMediumHighVery HighNot MappedWater BodyRodgers Creek FaultConcealedInferredApproximateWell LocatedC o n f i d e n t i a l0 0.5 1 2 3 4 MilesTannery CreekThurston CreekNolan CreekEbabias CreekCotati 2Copeland CreekCotati 3Wilfred BoosterStationCrane CreekPetaluma 3Lichau CreekEldridgeBoosterStationMill CreekStuart CreekEldridge Tanks(2 and 6 MG)Wilson CreekSonoma 3Agua Caliente CreekGossage CreekArroyo SecoAmericano CreekCotati Tanks(6, 12 and 18 MG)Petaluma 4Willow BrookEly BoosterStationPetaluma 5Lewis CreekCarriger CreekFelder CreekRodgers CreekSONOMA CRSonoma Tanks(2 and 8 MG)Nathanson CreekSTEMPLE CRFowler CreekLynch CreekADOBE CRChamplin CreekSchell SloughMarin AqueductTOLAY CRKastania Tank(12 MG)Kastania BoosterStationPETALUMA RFigure 9

Press CreekDowdall CreekLivereau CreekFife CreekRUSSIAN RRUSSIAN RWohler IntertieRussian River Well FieldMirabel ChlorinationInflatable Damand RDSRiver Road Chlorine andCorrosion ControlFay CreekDutch Bill CreekSmith CreekDuvoul CreekGrab CreekLancel CreekSALMON CRPorter CreekMirabelCollectors(No. 3, 4 and 5)GREEN VALLEY CRPurrington CreekWohler Collectors(No.1 and 2)ForestvilleBoosterStationRUSSIAN RCotati 1ForestvilleAqueductForestville Tanks(0.3 and 1 MG)Atascadero CreekOccidentalRoadWellWindsor CreekPool CreekWohler Chlorination andCorrosion ControlSANTA ROSA CRKawana 1Kawana SpringsBooster StationSebastopolRoadWellKawana 2Todd RoadWellSanta Rosa 1Piner CreekSanta Rosa 2Santa Rosa 3MATANZAS CRMill CreekRincon CreekPetaluma 1Kawana 3Petaluma 2Ducker CreekHumbug CreekSonoma BoosterStation(No. 1 and 2)Sonoma 1Kawana SpringsTank(10 MG)RalphineTanks(6, 6, 6and 18 MG)Weeks CreekMARK WEST CRVan Buren CreekPorter CreekAnnadel Tank 1(2.5 MG)OakmontAnnadel Tank 2(3 MG)Yulupa CreekSonoma 2Calabazas CreekLegendSCWA FacilitiesFacility typeBooster StationChlorination FacilityCollector StationCorrosion Control FacilityDiversion StructureHydroWater MeterStorage TankRussian River Well FieldProduction WellsAqueductLandslide HazardAqueduct Node PointsLandslide Hazardvery few landslidesfew landslidesmany landslidesmostly landslideC o n f i d e n t i a l0 0.5 1 2 3 4 MilesTannery CreekThurston CreekNolan CreekEbabias CreekCotati 2Copeland CreekCotati 3Wilfred BoosterStationCrane CreekPetaluma 3Lichau CreekEldridgeBoosterStationMill CreekStuart CreekEldridge Tanks(2 and 6 MG)Wilson CreekSonoma 3Agua Caliente CreekGossage CreekArroyo SecoAmericano CreekCotati Tanks(6, 12 and 18 MG)Petaluma 4Willow BrookEly BoosterStationPetaluma 5Lewis CreekCarriger CreekFelder CreekRodgers CreekSONOMA CRSonoma Tanks(2 and 8 MG)Nathanson CreekSTEMPLE CRFowler CreekLynch CreekADOBE CRChamplin CreekSchell SloughMarin AqueductTOLAY CRKastania Tank(12 MG)Kastania BoosterStationPETALUMA RFigure 10

Press CreekDowdall CreekLivereau CreekRUSSIAN RRUSSIAN RFife CreekWohler IntertieRussian River Well FieldRUSSIAN RMirabel ChlorinationInflatable Damand RDSRiver Road Chlorine andCorrosion ControlFay CreekDutch Bill CreekSmith CreekDuvoul CreekGrab CreekLancel CreekSALMON CRPorter CreekMirabelCollectors(No. 3, 4 and 5)GREEN VALLEY CRPurrington CreekWohler Collectors(No.1 and 2)ForestvilleBoosterStationRUSSIAN RCotati 1ForestvilleAqueductForestville Tanks(0.3 and 1 MG)Atascadero CreekOccidentalRoadWellWindsor CreekPool CreekWohler Chlorination andCorrosion ControlKawana 1SANTA ROSA CRKawana SpringsBooster StationSebastopolRoadWellSanta Rosa 1Kawana 2Todd RoadWellPiner CreekSanta Rosa 2Santa Rosa 3MATANZAS CRMill CreekRincon CreekPetaluma 1Kawana 3Petaluma 2Ducker CreekHumbug CreekSonoma BoosterStation(No. 1 and 2)Sonoma 1Kawana SpringsTank(10 MG)RalphineTanks(6, 6, 6and 18 MG)Weeks CreekMARK WEST CRVan Buren CreekPorter CreekAnnadel Tank 1(2.5 MG)OakmontAnnadel Tank 2(3 MG)Yulupa CreekSonoma 2Calabazas CreekLegendSCWA FacilitiesFacility typeBooster StationChlorination FacilityCollector StationCorrosion Control FacilityDiversion StructureHydroWater MeterStorage TankRussian River Well FieldProduction WellsAqueductAqueduct Node PointsFlood HazardCreek crossingsFEMA Flood ZonesZone A (100 year flood)Zone X (500 year flood)Zone ANI (area not included)Zone D (undetermined but possible hazard)C o n f i d e n t i a l0 0.5 1 2 3 4 MilesTannery CreekThurston CreekNolan CreekEbabias CreekCotati 2Copeland CreekCotati 3Wilfred BoosterStationCrane CreekPetaluma 3Lichau CreekEldridgeBoosterStationMill CreekStuart CreekEldridge Tanks(2 and 6 MG)Wilson CreekSonoma 3Agua Caliente CreekGossage CreekArroyo SecoAmericano CreekCotati Tanks(6, 12 and 18 MG)Petaluma 4Willow BrookEly BoosterStationPetaluma 5Lewis CreekCarriger CreekFelder CreekRodgers CreekSONOMA CRSonoma Tanks(2 and 8 MG)Nathanson CreekSTEMPLE CRFowler CreekLynch CreekADOBE CRChamplin CreekSchell SloughMarin AqueductTOLAY CRKastania Tank(12 MG)Kastania BoosterStationPETALUMA RFigure 11

CONFIDENTIALLocation of damaging landslide.Historic Landslides in Sonoma County During 1997-98 El Nino RainstormsFigure 12

Press CreekDowdall CreekLivereau CreekFife CreekWohler IntertieMirabel ChlorinationInflatable Damand RDSRUSSIAN RRUSSIAN RRussian River Well FieldRiver Road Chlorine andCorrosion ControlFay CreekDutch Bill CreekRUSSIAN RSmith CreekDuvoul CreekGrab CreekLancel CreekSALMON CRPorter CreekMirabelCollectors(No. 3, 4 and 5)GREEN VALLEY CRPurrington CreekWohler Collectors(No.1 and 2)ForestvilleBoosterStationRUSSIAN RCotati 1ForestvilleAqueductForestville Tanks(0.3 and 1 MG)Atascadero CreekOccidentalRoadWellWindsor CreekPool CreekWohler Chlorination andCorrosion ControlSANTA ROSA CRKawana 1Kawana SpringsBooster StationSebastopolRoadWellKawana 2Todd RoadWellSanta Rosa 1Piner CreekSanta Rosa 2Santa Rosa 3MATANZAS CRMill CreekRincon CreekPetaluma 1Kawana 3Petaluma 2Ducker CreekHumbug CreekSonoma BoosterStation(No. 1 and 2)Sonoma 1Kawana SpringsTank(10 MG)RalphineTanks(6, 6, 6and 18 MG)Weeks CreekMARK WEST CRVan Buren CreekPorter CreekAnnadel Tank 1(2.5 MG)OakmontAnnadel Tank 2(3 MG)Yulupa CreekSonoma 2Calabazas CreekLegendSCWA FacilitiesFacility typeDebris Flow HazardBooster StationChlorination FacilityCollector StationCorrosion Control FacilityDiversion StructureHydroWater MeterStorage TankRussian River Well FieldProduction WellsAqueductAqueduct Node PointsPrincipal predicted debris-flow source areas1982 debris-flow sourceslimit of mapping of 1982 debris-flow sourcesC o n f i d e n t i a l0 0.5 1 2 3 4 MilesTannery CreekThurston CreekNolan CreekEbabias CreekCotati 2Copeland CreekCotati 3Wilfred BoosterStationCrane CreekPetaluma 3Lichau CreekEldridgeBoosterStationMill CreekStuart CreekEldridge Tanks(2 and 6 MG)Wilson CreekSonoma 3Agua Caliente CreekGossage CreekArroyo SecoAmericano CreekCotati Tanks(6, 12 and 18 MG)Petaluma 4Willow BrookEly BoosterStationPetaluma 5Lewis CreekCarriger CreekFelder CreekRodgers CreekSONOMA CRSonoma Tanks(2 and 8 MG)Nathanson CreekSTEMPLE CRFowler CreekLynch CreekADOBE CRChamplin CreekSchell SloughMarin AqueductTOLAY CRKastania Tank(12 MG)Kastania BoosterStationPETALUMA RFigure 13

Wohler IntertieRussian River Well FieldMirabel ChlorinationInflatable Damand RDSRiver Road Chlorine andCorrosion ControlWohler Collectors(No.1 and 2)MirabelCollectors(No. 3, 4 and 5)ForestvilleBoosterStationCotati 1ForestvilleAqueductForestville Tanks(0.3 and 1 MG)Wohler Chlorination andCorrosion ControlOccidentalRoadWellKawana 1Kawana SpringsBooster StationSebastopolRoadWellKawana 2Todd RoadWellSanta Rosa 1Santa Rosa 2Santa Rosa 3Petaluma 1Kawana 3Petaluma 2Sonoma 1Kawana SpringsTank(10 MG)Sonoma BoosterStation(No. 1 and 2)RalphineTanks(6, 6, 6and 18 MG)Annadel Tank 1(2.5 MG)OakmontAnnadel Tank 2(3 MG)Sonoma 2LegendConcrete CorrosionPotentialSCWA FacilitiesFacility typeBooster StationChlorination FacilityCollector StationCorrosion Control FacilityDiversion StructureHydroWater MeterStorage TankRussian River Well FieldProduction WellsAqueductAqueduct Node PointsConcrete Corrosion PotentialHighModerateLowC o n f i d e n t i a l0 0.5 1 2 3 4 MilesCotati 2Wilfred BoosterStationPetaluma 3EldridgeBoosterStationEldridge Tanks(2 and 6 MG)Cotati 3Sonoma 3Cotati Tanks(6, 12 and 18 MG)Petaluma 4Ely BoosterStationSonoma Tanks(2 and 8 MG)Petaluma 5Marin AqueductKastania Tank(12 MG)Kastania BoosterStationFigure 14

Wohler IntertieRussian River Well FieldMirabel ChlorinationInflatable Damand RDSRiver Road Chlorine andCorrosion ControlWohler Collectors(No.1 and 2)MirabelCollectors(No. 3, 4 and 5)ForestvilleBoosterStationCotati 1ForestvilleAqueductForestville Tanks(0.3 and 1 MG)Wohler Chlorination andCorrosion ControlOccidentalRoadWellKawana 1Kawana SpringsBooster StationSebastopolRoadWellKawana 2Todd RoadWellSanta Rosa 1Santa Rosa 2Santa Rosa 3Petaluma 1Kawana 3Petaluma 2Sonoma 1Kawana SpringsTank(10 MG)Sonoma BoosterStation(No. 1 and 2)RalphineTanks(6, 6, 6and 18 MG)Annadel Tank 1(2.5 MG)OakmontAnnadel Tank 2(3 MG)Sonoma 2Steel Corrosion PotentialLegendSCWA FacilitiesFacility typeBooster StationChlorination FacilityCollector StationCorrosion Control FacilityDiversion StructureHydroWater MeterStorage TankRussian River Well FieldProduction WellsAqueductAqueduct Node PointsSteel Corrosion PotentialHighModerateLowC o n f i d e n t i a l0 0.5 1 2 3 4 MilesCotati 2Wilfred BoosterStationPetaluma 3EldridgeBoosterStationEldridge Tanks(2 and 6 MG)Cotati 3Sonoma 3Cotati Tanks(6, 12 and 18 MG)Petaluma 4Ely BoosterStationSonoma Tanks(2 and 8 MG)Petaluma 5Marin AqueductKastania Tank(12 MG)Kastania BoosterStationFigure 15

Wohler IntertieRussian River Well FieldMirabel ChlorinationInflatable Damand RDSRiver Road Chlorine andCorrosion ControlMirabelCollectors(No. 3, 4 and 5)Wohler Collectors(No.1 and 2)ForestvilleBoosterStationCotati 1ForestvilleAqueductForestville Tanks(0.3 and 1 MG)Wohler Chlorination andCorrosion ControlOccidentalRoadWellKawana 1Kawana SpringsBooster StationSebastopolRoadWellKawana 2Todd RoadWellSanta Rosa 1Santa Rosa 2Santa Rosa 3Petaluma 1Kawana 3Petaluma 2Sonoma 1Kawana SpringsTank(10 MG)Sonoma BoosterStation(No. 1 and 2)RalphineTanks(6, 6, 6and 18 MG)Annadel Tank 1(2.5 MG)OakmontAnnadel Tank 2(3 MG)Sonoma 2LegendSCWA FacilitiesFacility typeBooster StationChlorination FacilityCollector StationCorrosion Control FacilityDiversion StructureHydroWater MeterStorage TankRussian River Well FieldProduction WellsAqueductAqueduct Node PointsFire ThreatFire ThreatLittle or no threatModerateHighVery highExtremeC o n f i d e n t i a l0 0.5 1 2 3 4 MilesCotati 2Wilfred BoosterStationPetaluma 3EldridgeBoosterStationEldridge Tanks(2 and 6 MG)Cotati 3Sonoma 3Cotati Tanks(6, 12 and 18 MG)Petaluma 4Ely BoosterStationSonoma Tanks(2 and 8 MG)Petaluma 5Marin AqueductKastania Tank(12 MG)Kastania BoosterStationFigure 16

1959 KELLY1952 MAZZINI2002 PINE1962 GROVES1961 ROADSIDE #41965 DELAITTRE1988 RIVER1991 GEYSERS FIRE1962 WIDOW CREEK1952 DX HUNTING CLUBHistoric Firesin Sonoma County1988 RIVER1978 RESORT1959 NORTON RANCH1950 SMITH1988 GEYSERS SERIES1991 GEYSERS FIRE1965 POCKET RANCHLegend1970 SCHOOL HOUSE CREEK1961 REMMELSCWA FacilitiesFacility typeFire Perimeter1954 HOOVER RIDGE1999 PG&E #22Booster StationChlorination FacilityCollector Station1986 WILLOW SPRINGS1972 BRADFORD MT.Corrosion Control Facility1959 SODA SPRINGS1959 HOLLOW TREE1960 LAS LOMAS FIRE1959 WINE CREEK1988 BOISE2001 CLAYTON1976 IDA CLAYTONDiversion StructureHydroWater Meter19731960 1965 P.G.& E.#101982 SILVERADOStorage Tank1959 V. RICHARDSON1952 HEDGPETH1960 MORRISON1964 C. HANLYRussian River Well FieldProduction Wells1993 GERSTLE1964 MILL CREEK1955 PALMER CREEKAqueductAqueduct Node PointsC o n f i d e n t i a l19571953 CHARLES19541954 CHARLES1959 MCCRAY RIDGE1950 P.G.& E. #41996 PORTER CREEK FIRE0 1 2 4 6 8 Miles1978 CREIGHTON RIDGE1961 ROADSIDE #441965 P.G.&E. #6Wohler IntertieRussian River Well FieldMirabel ChlorinationInflatable Damand RDSRiver Road Chlorine andCorrosion ControlWohler Collectors(No.1 and 2)MirabelCollectors(No. 3, 4 and 5)ForestvilleBoosterStationForestvilleAqueductForestville Tanks(0.3 and 1 MG)Cotati 1Wohler Chlorination andCorrosion ControlOccidentalRoadWellKawana 1Kawana SpringsBooster StationSebastopolRoadWellKawana 2Santa Rosa 1Santa Rosa 2Santa Rosa 3Petaluma 1Sonoma 1Kawana SpringsTank(10 MG)Sonoma BoosterStation(No. 1 and 2)RalphineTanks(6, 6, 6and 18 MG)Annadel Tank 1(2.5 MG)1994 PG&E #24OakmontAnnadel Tank 2(3 MG)Sonoma 21965 P.G.& E.#7Todd RoadWellKawana 3Petaluma 21964 NUNS CANYON1961 ROBERTSONCotati 2Wilfred BoosterStationPetaluma 3EldridgeBoosterStationEldridge Tanks(2 and 6 MG)1996 PG&E #8Cotati 31965 P.G.& E.#5Sonoma 31980 GEHRICKECotati Tanks(6, 12 and 18 MG)Petaluma 41991 CARMODYEly BoosterStationPetaluma 51961 P.G.&E. #5Sonoma Tanks(2 and 8 MG)1972 ARROWHEAD1963 LANZIMarin Aqueduct2001 DUMP1965 ANDERSONKastania Tank(12 MG)Kastania BoosterStation1968 "D" STREET1966 LES CORDA RANCHFigure 17

CONFIDENTIALGeographic distribution of tornadoes based on a total number of tornado events per one degree of latitude and longitude: 1954-1983Source: Federal Emergency Management Agency – Multi-Hazard Identification and Risk AssessmentTornado HazardFigure 18

Blue Jay Creek!(Coleman Valley CreekHot Springs CreekPorterfield CreekGalloway CreekWhite CreekCrocker CreekOsser CreekBIG SULPHUR CRIcaria CreekLITTLE SULPHUR CRBrush CreekGill CreekFlat Ridge CreekBUCKEYE CRBarrelli CreekSoda Springs CreekBurns Creek!(!( !( !( !(!(!(Sea RanchSanitation ZoneGeyservilleSanitation ZoneDutcher CreekGrasshopper CreekMiller CreekLegendDRY CRBear CreekRancheria Creek!(!(SAUSAL CRHouse Creektu 128tu 1 §¨¦ 101Russian River CountySanitation DistrictAirport / Larkfield / WikiupSanitation Zone!(!(!(!(!(!( !( tu 116 !(!( Forestville County!(Sanitation District!(!( Graton SanitationZone!(!(!(!( Occidental CountySanitation Districttu 12!(South Park CountySanitation District!(!(!(Copeland CreekSonoma ValleySanitation District!(Pengrove SanitationZonetu 116tu 121!(!(Lift StationFault MapTombs CreekMill StreamMcDonnell CreekStrawberry CreekWaste Water Treatment PlantBluegum CreekFall CreekSanitation District/Zone BoundaryBriggs CreekCoon CreekGird CreekWillow Springs CreekFuller CreekBritain CreekYellowjacket CreekMAACAMA CRWine CreekChapman BranchRedwood Log CreekWARM SPRINGSFRANZ CRS A N A N D R E A S F A U L TM A A C A M A F A U L TPena CreekDanfield CreekKelley CreekPechaco CreekCedar CreekRedwood CreekBidwell CreekWallace CreekWoods CreekSulphur CreekAngel CreekDevil CreekBrooks CreekGray CreekRed Slide CreekMcKenzie CreekMarshall CreekMILL CRBarnes CreekFelta CreekBearpen CreekMiller CreekGilliam CreekThompson CreekWarren CreekPorter CreekWindsor CreekWard CreekCarson CrPress CreekOsborne CreekBlack Rock CreekHumbug CreekPool CreekFife Creek# Hulbert CreekMill CreekTurner CanyonTimber Cove CreekMARK WEST CRHobson CreekRUSSIAN RMission CreekVan Buren CreekWeeks CreekSANTA ROSA CRDucker CreekRincon CreekPiner CreekSmith CreekAUSTIN CROrrs CreekSheephouse CreekRussian GulchBohemian CreekMATANZAS CRPurrington CreekDutch Bill CreekWillow CreekAtascadero CreekFurlong GulchCalabazas CreekRough CreekSONOMA CRYulupa CreekCarriger CreekR O D G E R S C R E E K F A U L TFay CreekFinley CreekScotty CreekStuart CreekNolan CreekThurston CreekTannery CreekCrane CreekSALMON CREbabias CreekGossage CreekCheney GulchQuinlan GulchJohnson GulchArroyo SecoWillow BrookLichau CreekAmericano CreekPACIFIC OCEANRodgers CreekSTEMPLE CRFelder CreekLynch CreekChamplin CreekPETALUMA R!(FaultsGeologic AgeHistoricPena CreekHoloceneLatequaternaryFall CreekPrequaternaryQuaternaryRUSSIAN RSchoolhouse CreekRUSSIAN RRUSSIAN RRUSSIAN RPACIFIC OCEANADOBE CRSchultz SloughTOLAY CRPorter CreekFranchini CreekStewarts CreekLittle CreekGUALALA R, S FKROCKPILE CR³for the Agency's Service Area0 1 2 3 Miles*Sanitation Districts/Zones are encircled for emphasisFault Map for the Agency’s Sanitation System Service AreaFigure 19

Blue Jay Creek!(Coleman Valley CreekPorterfield Creek!(!( !( !( !(!(!(Sea RanchSanitation ZoneGeyservilleSanitation ZoneDRY CR!(!(Ground Shaking HazardMapHot Springs CreekGalloway CreekWhite CreekCrocker CreekOsser CreekBIG SULPHUR CRIcaria CreekLITTLE SULPHUR CRBrush CreekGill CreekFlat Ridge CreekBUCKEYE CRRancheria CreekTombs CreekSAUSAL CRBriggs CreekGird CreekMAACAMA CRWARM SPRINGSHouse Creektu 128tu 1 §¨¦ 101Russian River CountySanitation DistrictAirport / Larkfield / WikiupSanitation Zone!(!(!(!(!(!( !( tu 116 !(!( Forestville County!(Sanitation District!(!( Graton SanitationZone!(!(!(!( Occidental CountySanitation Districttu 12!(South Park CountySanitation District!(!(!(Copeland CreekSonoma ValleySanitation District!(Pengrove SanitationZonetu 116tu 121FRANZ CRS A N A N D R E A S F A U L TM A A C A M A F A U L TPena CreekGray CreekMarshall CreekMILL CRFelta CreekPorter CreekWindsor CreekWard CreekPool CreekFife CreekMARK WEST CRRUSSIAN RSANTA ROSA CRRincon CreekPiner CreekAUSTIN CRDutch Bill CreekWillow CreekAtascadero CreekSONOMA CRCarriger CreekR O D G E R S C R E E K F A U L TFay CreekStuart CreekNolan CreekCrane CreekSALMON CREbabias CreekBarrelli CreekSoda Springs CreekDutcher CreekGrasshopper CreekLegendBurns CreekMiller Creek!(!(Lift StationBear CreekWaste Water Treatment PlantMill StreamMcDonnell CreekStrawberry CreekBluegum CreekFall CreekSanitation District/Zone BoundaryPeak Ground AccelerationCoon CreekPena CreekWillow Springs CreekBidwell CreekWallace CreekMill CreekMATANZAS CRArroyo SecoWillow BrookLichau CreekAmericano CreekRodgers CreekSTEMPLE CRFelder CreekLynch CreekFuller CreekBritain CreekYellowjacket CreekWine CreekChapman BranchRedwood Log CreekFall CreekCedar CreekDanfield CreekKelley CreekPechaco CreekRedwood CreekWoods CreekSulphur CreekAngel CreekDevil CreekBrooks CreekRed Slide CreekMcKenzie CreekBarnes CreekBearpen CreekMiller CreekGilliam CreekThompson CreekWarren CreekRUSSIAN RCarson CrPress CreekOsborne CreekSchoolhouse CreekBlack Rock CreekHumbug Creek# Hulbert CreekTurner CanyonTimber Cove CreekHobson CreekMission CreekVan Buren CreekWeeks CreekDucker CreekSmith CreekRUSSIAN ROrrs CreekSheephouse CreekRussian GulchBohemian CreekRUSSIAN RRUSSIAN RPurrington CreekFurlong GulchCalabazas CreekRough CreekYulupa CreekFinley CreekScotty CreekThurston CreekTannery CreekGossage CreekCheney GulchQuinlan GulchJohnson GulchPACIFIC OCEANPACIFIC OCEANChamplin CreekPETALUMA R!(< 20 %g20 %g - 30 %g30 %g - 40 %g40 %g - 50 %g50 %g - 60 %g60 %g - 70 %g70 %g - 80 %gADOBE CRSchultz SloughTOLAY CRPorter CreekFranchini CreekStewarts CreekLittle CreekGUALALA R, S FKROCKPILE CR³0 1 2 3 Miles*Sanitation Districts/Zones are encircled for emphasisGround Shaking Hazard Map (Sanitation System)Figure 20

Blue Jay Creek!(Coleman Valley CreekPorterfield Creek!(!( !( !( !(!(!(Sea RanchSanitation ZoneLiquefaction andLateral Spread HazardHot Springs CreekWhite CreekCrocker CreekBIG SULPHUR CRIcaria CreekLITTLE SULPHUR CRBrush CreekGill CreekBarrelli CreekBurns CreekGeyservilleSanitation ZoneDutcher CreekDRY CR!(!(Legend!(!(§¨¦ 101Bear CreekRancheria CreekTombs CreekMill StreamMcDonnell CreekStrawberry CreekBluegum CreekSAUSAL CRFall CreekBriggs CreekCoon CreekGird CreekBritain CreekWillow Springs CreekMiller CreekMAACAMA CRWARM SPRINGSHouse Creektu 128Russian River CountySanitation DistrictAirport / Larkfield / WikiupSanitation Zone!(!(!(!(!(!( !( tu 116 !(!( Forestville County!(Sanitation District!(!( Graton SanitationZone!(tu 1 !(!(!( Occidental CountySanitation Districttu 12!(South Park CountySanitation District!(!(!(Copeland CreekSonoma ValleySanitation District!(Pengrove SanitationZonetu 116tu 121Lift StationWaste Water Treatment PlantSanitation District/Zone BoundaryLiquefaction PotentialLIQYellowjacket CreekWine CreekFRANZ CRM A A C A M A F A U L THoot Owl CreekRedwood Log CreekPena CreekDanfield CreekGray CreekMILL CRKelley CreekPechaco CreekCedar CreekRedwood CreekBidwell CreekWallace CreekDevil CreekFelta CreekPorter CreekWindsor CreekWard CreekPool CreekFife CreekMill CreekMARK WEST CRRUSSIAN RSANTA ROSA CRRincon CreekPiner CreekWoods CreekSulphur CreekBrooks CreekBarnes CreekBearpen CreekGilliam CreekThompson CreekCarson CrPress CreekBlack Rock CreekHumbug Creek# Hulbert CreekHobson CreekMission CreekVan Buren CreekWeeks CreekDucker CreekSmith CreekAUSTIN CROrrs CreekSheephouse CreekMATANZAS CRPurrington CreekDutch Bill CreekWillow CreekAtascadero CreekFurlong GulchCalabazas CreekRough CreekSONOMA CRYulupa CreekCarriger CreekR O D G E R S C R E E K F A U L TFay CreekFinley CreekScotty CreekStuart CreekNolan CreekThurston CreekTannery CreekCrane CreekSALMON CREbabias CreekGossage CreekCheney GulchQuinlan GulchJohnson GulchArroyo SecoWillow BrookLichau CreekAmericano CreekRodgers CreekSTEMPLE CRFelder CreekLynch CreekChamplin CreekPETALUMA R!(Very LowPena CreekLowMediumChapman BranchFall CreekHighVery HighNot MappedWater BodyAngel CreekRed Slide CreekRUSSIAN ROsborne CreekSchoolhouse CreekTurner CanyonRUSSIAN RRussian GulchBohemian CreekRUSSIAN RRUSSIAN RPACIFIC OCEANPACIFIC OCEANADOBE CRSchultz SloughTOLAY CRGalloway CreekMcKenzie CreekOsser CreekFlat Ridge CreekBUCKEYE CRSoda Springs CreekGrasshopper CreekFuller CreekMarshall CreekMiller CreekS A N A N D R E A S F A U L TWarren CreekWildcat CreekTimber Cove CreekPorter CreekFranchini CreekStewarts CreekLittle CreekGUALALA R, S FKROCKPILE CR³0 1 2 3 Miles*Sanitation Districts/Zones are encircled for emphasisLiquefaction and Lateral Spread Hazard Map (Sanitation System)Figure 21

Blue Jay Creek!(Coleman Valley CreekHot Springs CreekPorterfield CreekGalloway CreekWhite CreekCrocker CreekOsser CreekBIG SULPHUR CRIcaria CreekLITTLE SULPHUR CRBUCKEYE CR!(!( !( !( !(!(!(Sea RanchSanitation ZoneGeyservilleSanitation ZoneDRY CR!(!(SAUSAL CRHouse CreekBrush CreekGill CreekFlat Ridge Creektu 128tu 1 §¨¦ 101Russian River CountySanitation DistrictAirport / Larkfield / WikiupSanitation Zone!(!(!(!(!(!( !( tu 116 !(!( Forestville County!(Sanitation District!(!( Graton SanitationZone!(!(!(!( Occidental CountySanitation Districttu 12!(South Park CountySanitation District!(!(!(Copeland CreekSonoma ValleySanitation District!(Pengrove SanitationZonetu 116tu 121LegendTombs CreekBriggs CreekGird CreekMAACAMA CRWARM SPRINGSPena CreekFRANZ CRGray CreekMarshall CreekMILL CRPorter CreekWindsor CreekWard CreekPool CreekFife CreekMARK WEST CRRUSSIAN RSANTA ROSA CRRincon CreekPiner CreekAUSTIN CRDutch Bill CreekWillow CreekAtascadero CreekFay CreekSONOMA CRCrane CreekSALMON CREbabias CreekBarrelli CreekSoda Springs Creek!(!(Landslide HazardDutcher CreekGrasshopper CreekLift StationBurns CreekBear CreekRancheria CreekMill StreamMcDonnell CreekStrawberry CreekBluegum CreekFall CreekCoon CreekBidwell CreekWallace CreekFelta CreekMill CreekMATANZAS CRStuart CreekNolan CreekCarriger CreekArroyo SecoWillow BrookLichau CreekAmericano CreekRodgers CreekSTEMPLE CRFelder CreekLynch CreekFuller CreekBritain CreekWillow Springs CreekMiller CreekWaste Water Treatment PlantSanitation District/Zone BoundaryPena CreekYellowjacket CreekWine CreekChapman BranchRedwood Log CreekCedar CreekDanfield CreekKelley CreekPechaco CreekRedwood CreekWoods CreekSulphur CreekAngel CreekDevil CreekBrooks CreekRed Slide CreekMcKenzie CreekBarnes CreekBearpen CreekMiller CreekGilliam CreekThompson CreekWarren CreekCarson CrPress CreekOsborne CreekSchoolhouse CreekBlack Rock CreekHumbug Creek# Hulbert CreekTurner CanyonTimber Cove CreekHobson CreekMission CreekVan Buren CreekWeeks CreekDucker CreekSmith CreekOrrs CreekSheephouse CreekRussian GulchBohemian CreekRUSSIAN RPurrington CreekFurlong GulchCalabazas CreekRough CreekYulupa CreekFinley CreekScotty CreekThurston CreekTannery CreekGossage CreekCheney GulchQuinlan GulchJohnson GulchPACIFIC OCEANChamplin CreekPETALUMA R!(Landslide Hazardvery few landslidesfew landslidesmany landslidesmostly landslideFall CreekRUSSIAN RRUSSIAN RRUSSIAN RPACIFIC OCEANADOBE CRSchultz SloughTOLAY CRPorter CreekFranchini CreekStewarts CreekLittle CreekGUALALA R, S FKROCKPILE CR³0 1 2 3 Miles*Sanitation Districts/Zones are encircled for emphasisLandslide Hazard Map (Sanitation System)Figure 22

Blue Jay Creek!(Coleman Valley CreekHot Springs CreekPorterfield CreekGalloway CreekWhite CreekCrocker CreekOsser CreekBIG SULPHUR CRIcaria CreekLITTLE SULPHUR CRBUCKEYE CR!(!( !( !( !(!(!(Sea RanchSanitation ZoneGeyservilleSanitation ZoneDRY CR!(!(SAUSAL CRHouse CreekBrush CreekGill CreekFlat Ridge Creektu 128tu 1 §¨¦ 101Russian River CountySanitation DistrictAirport / Larkfield / WikiupSanitation Zone!(!(!(!(!(!( !( tu 116 !(!( Forestville County!(Sanitation District!(!( Graton SanitationZone!(!(!(!( Occidental CountySanitation Districttu 12!(South Park CountySanitation District!(!(!(Copeland CreekSonoma ValleySanitation District!(Pengrove SanitationZonetu 116tu 121LegendTombs CreekBriggs CreekGird CreekMAACAMA CRWARM SPRINGSPena CreekFRANZ CRGray CreekMarshall CreekMILL CRPorter CreekWindsor CreekWard CreekPool CreekFife CreekMARK WEST CRRUSSIAN RSANTA ROSA CRRincon CreekPiner CreekAUSTIN CRDutch Bill CreekWillow CreekAtascadero CreekFay CreekSONOMA CRCrane CreekSALMON CREbabias CreekBarrelli CreekSoda Springs Creek!(!(Flood HazardLift StationBurns CreekDutcher CreekGrasshopper CreekWaste Water Treatment PlantBear CreekRancheria CreekMill StreamMcDonnell CreekStrawberry CreekBluegum CreekFall CreekCoon CreekBidwell CreekWallace CreekFelta CreekMill CreekMATANZAS CRStuart CreekNolan CreekCarriger CreekArroyo SecoWillow BrookLichau CreekAmericano CreekRodgers CreekSTEMPLE CRFelder CreekLynch CreekFuller CreekBritain CreekWillow Springs CreekMiller CreekSanitation District/Zone BoundaryFEMA Flood ZonesZone A (100 year flood)Pena CreekZone X (500 year flood)Zone ANI (area not included)Yellowjacket CreekWine CreekChapman BranchRedwood Log CreekFall CreekZone D (undetermined but possible hazard)Cedar CreekDanfield CreekKelley CreekPechaco CreekRedwood CreekWoods CreekSulphur CreekAngel CreekDevil CreekBrooks CreekRed Slide CreekMcKenzie CreekBarnes CreekBearpen CreekMiller CreekGilliam CreekThompson CreekWarren CreekRUSSIAN RCarson CrPress CreekOsborne CreekSchoolhouse CreekBlack Rock CreekHumbug Creek# Hulbert CreekTurner CanyonTimber Cove CreekHobson CreekMission CreekVan Buren CreekWeeks CreekDucker CreekSmith CreekRUSSIAN ROrrs CreekSheephouse CreekRussian GulchBohemian CreekRUSSIAN RRUSSIAN RPurrington CreekFurlong GulchCalabazas CreekRough CreekYulupa CreekFinley CreekScotty CreekThurston CreekTannery CreekGossage CreekCheney GulchQuinlan GulchJohnson GulchPACIFIC OCEANPACIFIC OCEANChamplin CreekPETALUMA R!(ADOBE CRSchultz SloughTOLAY CRPorter CreekFranchini CreekStewarts CreekLittle CreekGUALALA R, S FKROCKPILE CR³0 1 2 3 Miles*Sanitation Districts/Zones are encircled for emphasisFlood Hazard Map (Sanitation System)Figure 23

Blue Jay Creek!(Coleman Valley CreekHot Springs CreekPorterfield Creek!(!( !( !( !(!(!(Sea RanchSanitation ZoneGeyservilleSanitation ZoneDRY CR!(!(Debris Flow HazardGalloway CreekWhite CreekCrocker CreekOsser CreekBIG SULPHUR CRIcaria CreekLITTLE SULPHUR CRBUCKEYE CRSAUSAL CRHouse CreekBrush CreekGill CreekFlat Ridge Creektu 128tu 1 §¨¦ 101Russian River CountySanitation DistrictAirport / Larkfield / WikiupSanitation Zone!(!(!(!(!(!( !( tu 116 !(!( Forestville County!(Sanitation District!(!( Graton SanitationZone!(!(!(!( Occidental CountySanitation Districttu 12!(South Park CountySanitation District!(!(!(Copeland CreekSonoma ValleySanitation District!(Pengrove SanitationZonetu 116tu 121LegendRancheria CreekTombs CreekBriggs CreekGird CreekMAACAMA CRWARM SPRINGSPena CreekFRANZ CRGray CreekMarshall CreekMILL CRFelta CreekPorter CreekWindsor CreekWard CreekPool CreekFife CreekMARK WEST CRRUSSIAN RSANTA ROSA CRRincon CreekPiner CreekAUSTIN CRDutch Bill CreekWillow CreekAtascadero CreekFay CreekStuart CreekSONOMA CRNolan CreekCrane CreekSALMON CREbabias CreekBarrelli CreekSoda Springs Creek!(!(Lift StationBurns CreekDutcher CreekGrasshopper CreekBear CreekMill StreamMcDonnell CreekStrawberry CreekBluegum CreekFall CreekCoon CreekBidwell CreekWallace CreekMill CreekMATANZAS CRCarriger CreekArroyo SecoWillow BrookLichau CreekAmericano CreekRodgers CreekSTEMPLE CRFelder CreekLynch CreekFuller CreekBritain CreekWillow Springs CreekMiller CreekWaste Water Treatment PlantSanitation District/Zone BoundaryPrincipal predicted debris-flow source areaslimit of mapping of 1982 debris-flow sourcesPena Creek1982 debris-flow sourcesYellowjacket CreekWine CreekChapman BranchRedwood Log CreekFall CreekCedar CreekDanfield CreekKelley CreekPechaco CreekRedwood CreekWoods CreekSulphur CreekAngel CreekDevil CreekBrooks CreekRed Slide CreekMcKenzie CreekBarnes CreekBearpen CreekMiller CreekGilliam CreekThompson CreekWarren CreekRUSSIAN RCarson CrPress CreekOsborne CreekSchoolhouse CreekBlack Rock CreekHumbug Creek# Hulbert CreekTurner CanyonTimber Cove CreekHobson CreekMission CreekVan Buren CreekWeeks CreekDucker CreekSmith CreekRUSSIAN ROrrs CreekSheephouse CreekRussian GulchBohemian CreekRUSSIAN RRUSSIAN RPurrington CreekFurlong GulchCalabazas CreekRough CreekYulupa CreekFinley CreekScotty CreekThurston CreekTannery CreekGossage CreekCheney GulchQuinlan GulchJohnson GulchPACIFIC OCEANPACIFIC OCEANChamplin CreekPETALUMA R!(ADOBE CRSchultz SloughTOLAY CRPorter CreekFranchini CreekStewarts CreekLittle CreekGUALALA R, S FKROCKPILE CR³0 1 2 3 Miles*Sanitation Districts/Zones are encircled for emphasisDebris Flow Hazard Map (Sanitation System)Figure 24

Concrete Corrosion Protection Map (Sanitation System)Figure 25

Steel Corrosion Protection Map (Sanitation System)Figure 26

³!( !( !(!( !(Fire Threat!( !(Sea RanchSanitation ZoneGeyservilleSanitation Zone!( !(Legend!(!(Fire ThreatLift StationWaste Water Treatment PlantSanitation District/Zone BoundaryLittle or no threatModerateHighVery high!(!(!(!(Russian River CountySanitation District!(!(!(!(!(tu 1 tu 116 tu 12Airport / Larkfield / WikiupSanitation Zone!(Forestville CountySanitation Districttu 128 tu 121Extreme0 1 2 3 Miles*Sanitation Districts/Zones are encircled for emphasis§¨¦ 101!(!(!(!(!(Graton SanitationZone!(!(Occidental CountySanitation DistrictSouth Park CountySanitation District!(!(!(!(Sonoma ValleySanitation DistrictPengrove SanitationZone!(!(tu 116Fire Threat Map (Sanitation System)Figure 27

1988 RIVER³!( !( !(!( !(1959 KELLY1959 NORTON RANCH1950 SMITH1988 RIVER1978 RESORT1988 GEYSERS SERIES1991 GEYSERS FIRE1965 POCKET RANCH1961 REMMELHistoric Firesin Sonoma County!( !(Sea RanchSanitation Zone1954 HOOVER RIDGE1970 SCHOOL HOUSE CREEKGeyservilleSanitation Zone!( !(1999 PG&E #22Legend!(!(Lift StationWaste Water Treatment PlantSanitation District/Zone Boundary1986 WILLOW SPRINGS1972 BRADFORD MT.Fire Perimeter1959 SODA SPRINGS1959 HOLLOW TREE1960 LAS LOMAS FIRE1959 WINE CREEK2001 CLAYTON0 1 2 3 Miles1988 BOISE1976 IDA CLAYTON*Sanitation Districts/Zones are encircled for emphasis1960 1965 P.G.& E.#101982 SILVERADO19731959 V. RICHARDSON1960 MORRISON1964 C. HANLY1952 HEDGPETH1964 MILL CREEK1993 GERSTLE1955 PALMER CREEK19571953 CHARLES19541954 CHARLES1959 MCCRAY RIDGE§¨¦ 1011950 P.G.& E. #41996 PORTER CREEK FIRE1978 CREIGHTON RIDGE1961 ROADSIDE #44!(!(!(!(Russian River CountySanitation District!(!(!(!(!(Airport / Larkfield / WikiupSanitation Zone!(Forestville CountySanitation District!(1994 PG&E #241965 P.G.&E. #6!(!(!(!(Graton SanitationZone!(!(Occidental CountySanitation District1965 P.G.& E.#71961 ROBERTSONtu 1 tu 116 tu 122003 LOFTYSouth Park CountySanitation District!(!(!(!(1964 NUNS CANYON1996 PG&E #81965 P.G.& E.#5Sonoma ValleySanitation District1980 GEHRICKE1991 CARMODY!(1972 ARROWHEADtu 128 tu 121Pengrove SanitationZone1961 P.G.&E. #5!(1963 LANZI2001 DUMPtu 1161965 ANDERSON1968 "D" STREET1966 LES CORDA RANCHHistoric Fires in Sonoma County (Sanitation System)Figure 28